fix below issues on mingw:
fix below issues on mingw:

1. compile warning:

D:\libgit2.git\src\win32\posix_w32.c: In function 'p_open':
D:\libgit2.git\src\win32\posix_w32.c:235:10: warning: 'mode_t' is promoted to 'int' when passed through '...' [enabled by default]
D:\libgit2.git\src\win32\posix_w32.c:235:10: note: (so you should pass 'int' not 'mode_t' to 'va_arg')
D:\libgit2.git\src\win32\posix_w32.c:235:10: note: if this code is reached, the program will abort

2. test crash.

3. the above two issues are same root cause. please see http://www.eskimo.com/~scs/cclass/int/sx11c.html

sygool/libgit2,saurabhsuniljain/libgit2,t0xicCode/libgit2,kissthink/libgit2,sygool/libgit2,linquize/libgit2,amyvmiwei/libgit2,sygool/libgit2,leoyanggit/libgit2,iankronquist/libgit2,yosefhackmon/libgit2,Tousiph/Demo1,evhan/libgit2,dleehr/libgit2,nokiddin/libgit2,iankronquist/libgit2,zodiac/libgit2.js,mhp/libgit2,sim0629/libgit2,KTXSoftware/libgit2,amyvmiwei/libgit2,sim0629/libgit2,MrHacky/libgit2,maxiaoqian/libgit2,Aorjoa/libgit2_maked_lib,Snazz2001/libgit2,mrksrm/Mingijura,t0xicCode/libgit2,sygool/libgit2,mingyaaaa/libgit2,linquize/libgit2,swisspol/DEMO-libgit2,maxiaoqian/libgit2,rcorre/libgit2,skabel/manguse,rcorre/libgit2,yongthecoder/libgit2,joshtriplett/libgit2,Tousiph/Demo1,stewid/libgit2,sim0629/libgit2,skabel/manguse,mhp/libgit2,skabel/manguse,t0xicCode/libgit2,chiayolin/libgit2,JIghtuse/libgit2,Tousiph/Demo1,jflesch/libgit2-mariadb,leoyanggit/libgit2,zodiac/libgit2.js,iankronquist/libgit2,kenprice/libgit2,magnus98/TEST,whoisj/libgit2,mcanthony/libgit2,falqas/libgit2,maxiaoqian/libgit2,leoyanggit/libgit2,evhan/libgit2,nokiddin/libgit2,jflesch/libgit2-mariadb,joshtriplett/libgit2,dleehr/libgit2,amyvmiwei/libgit2,nacho/libgit2,raybrad/libit2,MrHacky/libgit2,saurabhsuniljain/libgit2,jeffhostetler/public_libgit2,mcanthony/libgit2,spraints/libgit2,iankronquist/libgit2,Aorjoa/libgit2_maked_lib,ardumont/libgit2,yosefhackmon/libgit2,kenprice/libgit2,jamieleecool/ptest,KTXSoftware/libgit2,nacho/libgit2,sim0629/libgit2,yosefhackmon/libgit2,magnus98/TEST,joshtriplett/libgit2,amyvmiwei/libgit2,falqas/libgit2,sim0629/libgit2,maxiaoqian/libgit2,MrHacky/libgit2,since2014/libgit2,jflesch/libgit2-mariadb,mrksrm/Mingijura,since2014/libgit2,kissthink/libgit2,t0xicCode/libgit2,raybrad/libit2,jamieleecool/ptest,yosefhackmon/libgit2,KTXSoftware/libgit2,swisspol/DEMO-libgit2,t0xicCode/libgit2,jflesch/libgit2-mariadb,sygool/libgit2,Corillian/libgit2,mingyaaaa/libgit2,nokiddin/libgit2,mcanthony/libgit2,mhp/libgit2,kenprice/libgit2,JIghtuse/libgit2,skabel/manguse,Aorjoa/libgit2_maked_lib,mhp/libgit2,claudelee/libgit2,raybrad/libit2,saurabhsuniljain/libgit2,nokiddin/libgit2,swisspol/DEMO-libgit2,MrHacky/libgit2,KTXSoftware/libgit2,zodiac/libgit2.js,zodiac/libgit2.js,jeffhostetler/public_libgit2,JIghtuse/libgit2,Corillian/libgit2,oaastest/libgit2,saurabhsuniljain/libgit2,ardumont/libgit2,whoisj/libgit2,oaastest/libgit2,zodiac/libgit2.js,rcorre/libgit2,mingyaaaa/libgit2,Tousiph/Demo1,Snazz2001/libgit2,nacho/libgit2,yongthecoder/libgit2,oaastest/libgit2,whoisj/libgit2,jeffhostetler/public_libgit2,oaastest/libgit2,maxiaoqian/libgit2,swisspol/DEMO-libgit2,Corillian/libgit2,kenprice/libgit2,magnus98/TEST,t0xicCode/libgit2,iankronquist/libgit2,mhp/libgit2,claudelee/libgit2,ardumont/libgit2,skabel/manguse,maxiaoqian/libgit2,Tousiph/Demo1,mcanthony/libgit2,since2014/libgit2,magnus98/TEST,spraints/libgit2,Aorjoa/libgit2_maked_lib,ardumont/libgit2,saurabhsuniljain/libgit2,linquize/libgit2,linquize/libgit2,ardumont/libgit2,falqas/libgit2,Snazz2001/libgit2,MrHacky/libgit2,jflesch/libgit2-mariadb,evhan/libgit2,kissthink/libgit2,chiayolin/libgit2,Corillian/libgit2,oaastest/libgit2,sygool/libgit2,dleehr/libgit2,MrHacky/libgit2,since2014/libgit2,yongthecoder/libgit2,Tousiph/Demo1,dleehr/libgit2,Aorjoa/libgit2_maked_lib,chiayolin/libgit2,joshtriplett/libgit2,jflesch/libgit2-mariadb,kissthink/libgit2,mingyaaaa/libgit2,mingyaaaa/libgit2,JIghtuse/libgit2,dleehr/libgit2,mhp/libgit2,raybrad/libit2,stewid/libgit2,mrksrm/Mingijura,skabel/manguse,claudelee/libgit2,chiayolin/libgit2,mrksrm/Mingijura,claudelee/libgit2,stewid/libgit2,jeffhostetler/public_libgit2,linquize/libgit2,kissthink/libgit2,dleehr/libgit2,since2014/libgit2,mcanthony/libgit2,raybrad/libit2,falqas/libgit2,leoyanggit/libgit2,Snazz2001/libgit2,joshtriplett/libgit2,whoisj/libgit2,yosefhackmon/libgit2,jamieleecool/ptest,jeffhostetler/public_libgit2,spraints/libgit2,Snazz2001/libgit2,joshtriplett/libgit2,since2014/libgit2,iankronquist/libgit2,magnus98/TEST,amyvmiwei/libgit2,linquize/libgit2,kissthink/libgit2,stewid/libgit2,kenprice/libgit2,mingyaaaa/libgit2,claudelee/libgit2,leoyanggit/libgit2,saurabhsuniljain/libgit2,jamieleecool/ptest,swisspol/DEMO-libgit2,yosefhackmon/libgit2,rcorre/libgit2,mrksrm/Mingijura,yongthecoder/libgit2,spraints/libgit2,stewid/libgit2,rcorre/libgit2,JIghtuse/libgit2,ardumont/libgit2,KTXSoftware/libgit2,claudelee/libgit2,mrksrm/Mingijura,falqas/libgit2,yongthecoder/libgit2,Corillian/libgit2,whoisj/libgit2,chiayolin/libgit2,kenprice/libgit2,jeffhostetler/public_libgit2,falqas/libgit2,nokiddin/libgit2,spraints/libgit2,stewid/libgit2,leoyanggit/libgit2,Corillian/libgit2,yongthecoder/libgit2,Snazz2001/libgit2,mcanthony/libgit2,evhan/libgit2,oaastest/libgit2,JIghtuse/libgit2,magnus98/TEST,swisspol/DEMO-libgit2,rcorre/libgit2,sim0629/libgit2,KTXSoftware/libgit2,nokiddin/libgit2,chiayolin/libgit2,spraints/libgit2,nacho/libgit2,amyvmiwei/libgit2,whoisj/libgit2