I just updated to Xcode 8, and I can no longer build xml2-based applications. If I build a simple file and try to build it as follows:
c++ myapp.cc `xml2-config
@mnencia's answer almost worked for me, but the sed command didn't replace anything in the TLB files - the backups were the same as the modified files.
I ran this part of his command:
grep -ril /usr/lib/system/libsystem_symptoms.dylib /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/lib
Which identified the files referencing the removed library and modified them by hand.
YMMV