FindPkgConfig: document how multiple values are returned
The build fails for the cmake-based project qTox. The cause of the failure is the presence of -D_THREAD_SAFE;-pthread;-pthread in the flags passed to the compiler. I found that this failure is avoided by removing "-D_THREAD_SAFE" from this line in /usr/local/libdata/pkgconfig/x11.pc:
Cflags: -I${includedir} -D_THREAD_SAFE
It appears that cmake fails to strip semicolons when "-D_THREAD_SAFE" is present in the output of pkg-config.
OS: FreeBSD 11
Project: qTox