argp-standlone: build position independent code

Even though argp-standalone is built as a static library, it might get
linked in a shared library, so we must built it as
position-independent code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/argp-standalone/argp-standalone.mk

@@ -8,6 +8,9 @@ ARGP_STANDALONE_VERSION = 1.3
 ARGP_STANDALONE_SITE = http://www.lysator.liu.se/~nisse/archive
 ARGP_STANDALONE_INSTALL_STAGING = YES
 
+ARGP_STANDALONE_CONF_ENV = \
+	CFLAGS="$(TARGET_CFLAGS) -fPIC"
+
 define ARGP_STANDALONE_INSTALL_STAGING_CMDS
 	$(INSTALL) -D $(@D)/libargp.a $(STAGING_DIR)/usr/lib/libargp.a
 	$(INSTALL) -D $(@D)/argp.h $(STAGING_DIR)/usr/include/argp.h