[PATCH v1] libperf build: Always place libperf includes first

[Ian Rogers <irogers@google.com>]

When building tools/perf the CFLAGS can contain a directory for the
installed headers. As the headers may be being installed while
building libperf.a this can cause headers to be partially installed
and found in the include path while building an object file for
libperf.a. The installed header may reference other installed headers
that are missing given the partial nature of the install and then the
build fails with a missing header file. Avoid this by ensuring the
libperf source headers are always first in the CFLAGS.

Fixes: 314350491810 ("libperf: Make libperf.a part of the perf build")
Signed-off-by: Ian Rogers <irogers@google.com>
---
I started seeing these build failures in build-test post
commit c3030995f23b ("perf sched stats: Add record and rawdump support")
which increased the number of libperf header files and their
dependencies. It isn't correct that this patch fixes that patch, the
problem has existed as long as libperf which is why a much earlier
commit is in the Fixes tag.
---
 tools/lib/perf/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/perf/Makefile b/tools/lib/perf/Makefile
index 9692d0742ed0..32301a1d8f0c 100644
--- a/tools/lib/perf/Makefile
+++ b/tools/lib/perf/Makefile
@@ -50,9 +50,9 @@ INCLUDES = \
 -I$(srctree)/tools/include/uapi
 
 # Append required CFLAGS
+override CFLAGS := $(INCLUDES) $(CFLAGS)
 override CFLAGS += -g -Werror -Wall
 override CFLAGS += -fPIC
-override CFLAGS += $(INCLUDES)
 override CFLAGS += -fvisibility=hidden
 override CFLAGS += $(EXTRA_WARNINGS)
 override CFLAGS += $(EXTRA_CFLAGS)
-- 
2.53.0.rc1.225.gd81095ad13-goog