package infra: add -static to C/CXXFLAGS

Generic infra packages might not use LDFLAGS at all so add -static for
static builds to CFLAGS and CXXFLAGS too.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/Makefile.in

@@ -374,6 +374,8 @@ endif
 
 ifeq ($(BR2_PREFER_STATIC_LIB),y)
 SHARED_STATIC_LIBS_OPTS = --enable-static --disable-shared
+TARGET_CFLAGS += -static
+TARGET_CXXFLAGS += -static
 TARGET_LDFLAGS += -static
 else
 SHARED_STATIC_LIBS_OPTS = --enable-static --enable-shared