perf tools: Add an option to build without libbfd

Some distributions, like debian, don't link perf with libbfd. Add a
build flag to make this configuration buildable and testable.

This was inspired by:

  https://lore.kernel.org/linux-perf-users/20210910102307.2055484-1-tonyg@leastfixedpoint.com/T/#u

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: tony garnock-jones <tonyg@leastfixedpoint.com>
Link: http://lore.kernel.org/lkml/20210910225756.729087-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile.config

@@ -827,9 +827,11 @@ else
   endif
 endif
 
-ifeq ($(feature-libbfd), 1)
+
+ifndef NO_LIBBFD
+  ifeq ($(feature-libbfd), 1)
     EXTLIBS += -lbfd -lopcodes
-else
+  else
     # we are on a system that requires -liberty and (maybe) -lz
     # to link against -lbfd; test each case individually here
 
@@ -848,12 +850,13 @@ else
       endif
     endif
     $(call feature_check,disassembler-four-args)
-endif
+  endif
 
-ifeq ($(feature-libbfd-buildid), 1)
+  ifeq ($(feature-libbfd-buildid), 1)
     CFLAGS += -DHAVE_LIBBFD_BUILDID_SUPPORT
-else
+  else
     msg := $(warning Old version of libbfd/binutils things like PE executable profiling will not be available);
+  endif
 endif
 
 ifdef NO_DEMANGLE