Protect sha1_entry_pos call with mutex
Protect sha1_entry_pos call with mutex

There is an occasional assertion failure in sha1_entry_pos from
pack_entry_find_index when running threaded.  Holding the mutex
around the code that grabs the index_map data and processes it
makes this assertion failure go away.

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