perf build: Support llvm and clang support compiled in

Perf build suports llvm and clang support compiled in.
Test case 56 builtin clang support provides a test case
which is always skipped.

Link perf with the latest llvm and clang libraries and
enable this test case.

Use 'make LIBCLANGLLVM=1' to include this support.

V2: Add Library patch before -lclang-cpp

Output before:

  # ./perf test 56
  56: builtin clang support                  :
  56.1: builtin clang compile C source to IR : Skip (not compiled in)
  56.2: builtin clang compile C source to ELF object: Skip (not compiled in)

Output after:

  # ./perf test 56
  56: builtin clang support                          :
  56.1: builtin clang compile C source to IR         : Ok
  56.2: builtin clang compile C source to ELF object : Ok
  #

From Ian Rogers:

  Build tested with LLVM 14 and 15 using:
  BUILD_BPF_SKEL=1 LIBCLANGLLVM=1 LLVM_CONFIG=llvm-config-14
  BUILD_BPF_SKEL=1 LIBCLANGLLVM=1 LLVM_CONFIG=llvm-config-15

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lore.kernel.org/r/20230725150347.3479291-2-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile.config

@@ -331,7 +331,7 @@ CORE_CFLAGS += -Wall
 CORE_CFLAGS += -Wextra
 CORE_CFLAGS += -std=gnu11
 
-CXXFLAGS += -std=gnu++14 -fno-exceptions -fno-rtti
+CXXFLAGS += -std=gnu++17 -fno-exceptions -fno-rtti
 CXXFLAGS += -Wall
 CXXFLAGS += -Wextra
 CXXFLAGS += -fno-omit-frame-pointer

tools/perf/Makefile.perf

@@ -426,10 +426,7 @@ EXTLIBS := $(call filter-out,$(EXCLUDE_EXTLIBS),$(EXTLIBS))
 LIBS = -Wl,--whole-archive $(PERFLIBS) $(EXTRA_PERFLIBS) -Wl,--no-whole-archive -Wl,--start-group $(EXTLIBS) -Wl,--end-group
 
 ifeq ($(USE_CLANG), 1)
-  CLANGLIBS_LIST = AST Basic CodeGen Driver Frontend Lex Tooling Edit Sema Analysis Parse Serialization
-  CLANGLIBS_NOEXT_LIST = $(foreach l,$(CLANGLIBS_LIST),$(shell $(LLVM_CONFIG) --libdir)/libclang$(l))
-  LIBCLANG = $(foreach l,$(CLANGLIBS_NOEXT_LIST),$(wildcard $(l).a $(l).so))
-  LIBS += -Wl,--start-group $(LIBCLANG) -Wl,--end-group
+  LIBS += -L$(shell $(LLVM_CONFIG) --libdir) -lclang-cpp
 endif
 
 ifeq ($(USE_LLVM), 1)