[RFC] Fix python feature detection

[Joel Fernandes (Google)]

I am having a hard time building BPF samples by doing a make in
samples/bpf. While I am debugging that, I ran into the Python issue.
Even though the system has libpython2.7-dev:

If I just do a 'make' inside tools/build/feature/ I get:
Python.h: No such file or directory

This led me to this patch which fixes Python feature detection for me.
I am not sure if it is the right fix for Python since it is hardcoded
for Python version 2, but I thought it could be useful.

My system is a Debian buster release.

Cc: acme@xxxxxxxxxx
Cc: jolsa@xxxxxxxxxx
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
 tools/build/feature/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index 4b8244ee65ce..cde44cb38a5e 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -83,7 +83,7 @@ __BUILDXX = $(CXX) $(CXXFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(
 ###############################
 
 $(OUTPUT)test-all.bin:
-	$(BUILD) -fstack-protector-all -O2 -D_FORTIFY_SOURCE=2 -ldw -lelf -lnuma -lelf -laudit -I/usr/include/slang -lslang $(shell $(PKG_CONFIG) --libs --cflags gtk+-2.0 2>/dev/null) $(FLAGS_PERL_EMBED) $(FLAGS_PYTHON_EMBED) -DPACKAGE='"perf"' -lbfd -ldl -lz -llzma
+	$(BUILD) -fstack-protector-all -O2 -D_FORTIFY_SOURCE=2 -ldw -lelf -lnuma -lelf -laudit -I/usr/include/slang -lslang $(shell $(PKG_CONFIG) --libs --cflags gtk+-2.0 2>/dev/null) $(shell $(PKG_CONFIG) --libs --cflags python2 2>/dev/null) $(FLAGS_PERL_EMBED) $(FLAGS_PYTHON_EMBED) -DPACKAGE='"perf"' -lbfd -ldl -lz -llzma
 
 $(OUTPUT)test-hello.bin:
 	$(BUILD)
@@ -205,7 +205,7 @@ $(OUTPUT)test-libperl.bin:
 	$(BUILD) $(FLAGS_PERL_EMBED)
 
 $(OUTPUT)test-libpython.bin:
-	$(BUILD) $(FLAGS_PYTHON_EMBED)
+	$(BUILD) $(shell $(PKG_CONFIG) --libs --cflags python2 2>/dev/null) $(FLAGS_PYTHON_EMBED)
 
 $(OUTPUT)test-libpython-version.bin:
 	$(BUILD)
-- 
2.22.0.410.gd8fdbe21b5-goog