perf beauty: Allow the CC used in the arch errno names script to acccept CFLAGS

Allow the CC compiler to accept a CFLAGS environment variable.  This
doesn't change the code generated but makes it easier to integrate
running the shell script in build systems like bazel.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexios Zavras <alexios.zavras@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Li <liwei391@huawei.com>
Link: http://lore.kernel.org/lkml/20200306071110.130202-4-irogers@google.com
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/trace/beauty/arch_errno_names.sh

@@ -57,7 +57,7 @@ process_arch()
 	local arch="$1"
 	local asm_errno=$(asm_errno_file "$arch")
 
-	$gcc $include_path -E -dM -x c $asm_errno \
+	$gcc $CFLAGS $include_path -E -dM -x c $asm_errno \
 		|grep -hE '^#define[[:blank:]]+(E[^[:blank:]]+)[[:blank:]]+([[:digit:]]+).*' \
 		|awk '{ print $2","$3; }' \
 		|sort -t, -k2 -nu \