perf build: Get rid of LIB_INCLUDE variable

It has no use, so we can directly use the value for CFLAGS.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <david.ahern@oracle.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-ywyr5v962s32daq5hpgfkjap@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/config/Makefile

@@ -15,7 +15,6 @@ $(shell echo -n > .config-detected)
 detected     = $(shell echo "$(1)=y"       >> .config-detected)
 detected_var = $(shell echo "$(1)=$($(1))" >> .config-detected)
 
-LIB_INCLUDE := $(srctree)/tools/lib/
 CFLAGS := $(EXTRA_CFLAGS) $(EXTRA_WARNINGS)
 
 include $(src-perf)/config/Makefile.arch
@@ -320,7 +319,7 @@ endif
 
 CFLAGS += -I$(src-perf)/util
 CFLAGS += -I$(src-perf)
-CFLAGS += -I$(LIB_INCLUDE)
+CFLAGS += -I$(srctree)/tools/lib/
 
 CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE