Update bb10-pjsipdemo/pjbuildscripts/buildpjsip

for bb10 sdk version 10_0_9_1673, option --with-opencore-amrnb will be changed to --with-opencore-amr=DIR
Merge pull request #78 from nguyentran/patch-1

Update bb10-pjsipdemo/pjbuildscripts/buildpjsip