perf python: Ignore unused command line arguments when building with clang

Noticed after switching to python3 by default on some older fedora
releases:

  35    38.20 fedora:27                     : FAIL clang version 5.0.2 (tags/RELEASE_502/final)
    clang-5.0: error: argument unused during compilation: '-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1' [-Werror,-Wunused-command-line-argument]
    clang-5.0: error: argument unused during compilation: '-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1' [-Werror,-Wunused-command-line-argument]
    error: command 'clang' failed with exit status 1
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/scripts/perl/Perf-Trace-Util/Build

@@ -3,3 +3,7 @@ perf-y += Context.o
 CFLAGS_Context.o += $(PERL_EMBED_CCOPTS) -Wno-redundant-decls -Wno-strict-prototypes -Wno-bad-function-cast -Wno-declaration-after-statement -Wno-switch-enum
 CFLAGS_Context.o += -Wno-unused-parameter -Wno-nested-externs -Wno-undef
 CFLAGS_Context.o += -Wno-switch-default -Wno-shadow
+
+ifeq ($(CC_NO_CLANG), 1)
+  CFLAGS_Context.o += -Wno-unused-command-line-argument
+endif

tools/perf/util/setup.py

@@ -48,7 +48,9 @@ class install_lib(_install_lib):
 cflags = getenv('CFLAGS', '').split()
 # switch off several checks (need to be at the end of cflags list)
 cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls', '-DPYTHON_PERF' ]
-if not cc_is_clang:
+if cc_is_clang:
+    cflags += ["-Wno-unused-command-line-argument" ]
+else:
     cflags += ['-Wno-cast-function-type' ]
 
 src_perf  = getenv('srctree') + '/tools/perf'