package/heirloom-mailx: fix link issue with getopt

With NIOS2 toolchain, heirloom-mailx fail to build
due to missing -fPIC when linking with its own getopt.

Since static build for heirloom-mailx is disabled,
always pass -fPIC in CFLAGS.

Fixes:
http://autobuild.buildroot.net/results/333/33346f4555ed403bab7b739dd5d47814efa8eb4c

Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/heirloom-mailx/heirloom-mailx.mk

@@ -18,8 +18,11 @@ define HEIRLOOM_MAILX_CONFIGURE_CMDS
 	(cd $(@D); $(TARGET_CONFIGURE_OPTS) $(SHELL) ./makeconfig)
 endef
 
+# -fPIC is needed to build with NIOS2 toolchains.
 define HEIRLOOM_MAILX_BUILD_CMDS
-	$(TARGET_CONFIGURE_OPTS) $(MAKE) -C $(@D)
+	$(TARGET_CONFIGURE_OPTS) $(MAKE) \
+		CFLAGS="$(TARGET_CFLAGS) -fPIC" \
+		-C $(@D)
 endef
 
 define HEIRLOOM_MAILX_INSTALL_TARGET_CMDS