Build: Looking for YAJL's LD flags instead of CFLAGS
Build: Looking for YAJL's LD flags instead of CFLAGS

Original author: @LinuxJedi. Reported at #1077.

wafbuild/ModSecurity,wafbuild/ModSecurity,defanator/ModSecurity,defanator/ModSecurity,defanator/ModSecurity,SpiderLabs/ModSecurity,SpiderLabs/ModSecurity,SpiderLabs/ModSecurity,wafbuild/ModSecurity