kvm tools: Add test for -static libc present

Make sure the static binaries can be built.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
[ penberg@kernel.org: improve error message ]
Signed-off-by: Pekka Enberg <penberg@kernel.org>

Makefile

@@ -219,6 +219,9 @@ ifeq ($(call try-cc,$(SOURCE_AIO),$(FLAGS_AIO) -static),y)
 	LIBS_STATOPT	+= -laio
 endif
 
+ifneq ($(call try-build,$(SOURCE_STATIC),-static,),y)
+$(error No static libc found. Please install glibc-static package.)
+endif
 ###
 
 LIBS	+= -lrt

config/feature-tests.mak

@@ -166,3 +166,12 @@ int main(void)
 	return 0;
 }
 endef
+
+define SOURCE_STATIC
+#include <stdlib.h>
+
+int main(void)
+{
+	return 0;
+}
+endef

config/utilities.mak

@@ -186,3 +186,11 @@ try-cc = $(shell sh -c						  \
 	 echo "$(1)" |						  \
 	 $(CC) -x c - $(2) -o "$$TMP" > /dev/null 2>&1 && echo y; \
 	 rm -f "$$TMP"')
+
+# try-build
+# Usage: option = $(call try-build, source-to-build, cc-options, link-options)
+try-build = $(shell sh -c							\
+	'TMP="$(OUTPUT)$(TMPOUT).$$$$";						\
+	echo "$(1)" |								\
+	$(CC) -x c - $(2) $(3) -o "$$TMP" > /dev/null 2>&1 && echo y;		\
+	rm -f "$$TMP"')