Although --system-libs is expected to use after --libs, it can be used alone.
$ bin/llvm-config --ldflags
-L/path/to/llvm/objroot/lib
$ bin/llvm-config --libs object
-lLLVMObject -lLLVMSupport
$ bin/llvm-config --system-libs
(Blank line. "all" is assumed but nothing is printed.)
-lrt -ldl -ltinfo -lpthread -lz
$ bin/llvm-config --ldflags --libs --system-libs object
-L/path/to/llvm/objroot/lib
-lLLVMObject -lLLVMSupport
-lrt -ldl -ltinfo -lpthread -lz
It is reimplementation of r197380, and workaround for PR3347 and PR8449.
FIXME: Each LLVM component may have its dependent system libs.
llvm-svn: 197664