Fix some "signed/unsigned comparison" compilation warnings
Fix some "signed/unsigned comparison" compilation warnings

These warnings are issued by both gcc (-Wextra) and msvc (-W3).

Signed-off-by: Ramsay Jones <3e74413778ce9c8bebbbaedfd56741f6850faeaf@ramsay1.demon.co.uk>
Signed-off-by: Andreas Ericsson <1eabdaf488b3a3682bbca94c5f468f065cdfaf13@op5.se>

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