[PATCH 2/6] tools build: fix feature detection redefinion of build flags

[David Carrillo-Cisneros <davidcc@google.com>]

This change is a follow up of https://lkml.org/lkml/2017/2/2/16

The patch above avoided redefining CC, CXX and PKG_CONFIG in feature
detection. The patch was not merged due to a unsolved concern with
the -MD flag.

Later, commit c8c188679ccf ("tools build: Use the same CC for feature
  detection and actual build")
did the change for CC and CXX but not PKG_CONFIG.

This patch makes PKG_CONFIG consistent with CC and CXX and moves
the -MD to CFLAGS, as suggested by Jiri in the thread above.

Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
---
 tools/build/feature/Makefile | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 523e587fe05f..e35e4e5ad192 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -53,17 +53,17 @@ FILES=                                          \
 
 FILES := $(addprefix $(OUTPUT),$(FILES))
 
-CC ?= $(CROSS_COMPILE)gcc -MD
-CXX ?= $(CROSS_COMPILE)g++ -MD
-PKG_CONFIG := $(CROSS_COMPILE)pkg-config
+CC ?= $(CROSS_COMPILE)gcc
+CXX ?= $(CROSS_COMPILE)g++
+PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
 LLVM_CONFIG ?= llvm-config
 
 all: $(FILES)
 
-__BUILD = $(CC) $(CFLAGS) -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
+__BUILD = $(CC) $(CFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(LDFLAGS)
   BUILD = $(__BUILD) > $(@:.bin=.make.output) 2>&1
 
-__BUILDXX = $(CXX) $(CXXFLAGS) -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
+__BUILDXX = $(CXX) $(CXXFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
   BUILDXX = $(__BUILDXX) > $(@:.bin=.make.output) 2>&1
 
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-- 
2.12.2.715.g7642488e1d-goog