[PATCH] perf: allow forcing use of cplus_demangle

[Kyle McMartin <kyle@mcmartin.ca>]

For Fedora, I want to force perf to link against libiberty.a for
cplus_demangle, rather than libbfd.a for bfd_demangle due to licensing
insanity on binutils. (libiberty is LGPL2, libbfd is GPL3.)

If we just rely on autodetection, we'll end up with libbfd linked
against us, since they're both in binutils-static in the buildroot.

Signed-off-by: Kyle McMartin <kyle@redhat.com>
---
diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index bc0f670..429bace 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -541,6 +541,9 @@ endif
 
 ifdef NO_DEMANGLE
 	BASIC_CFLAGS += -DNO_DEMANGLE
+else ifdef HAVE_CPLUS_DEMANGLE
+	EXTLIBS += -liberty
+	BASIC_CFLAGS += -DHAVE_CPLUS_DEMANGLE
 else
 	has_bfd := $(shell sh -c "(echo '\#include <bfd.h>'; echo 'int main(void) { bfd_demangle(0, 0, 0); return 0; }') | $(CC) -x c - $(ALL_CFLAGS) -o $(BITBUCKET) $(ALL_LDFLAGS) $(EXTLIBS) -lbfd "$(QUIET_STDERR)" && echo y")