openswan: do not use -fPIE for static builds

-fPIE produces shared objects, and shared objects need "/lib/ld.so"
which won't be present on a statically built target. So, building
openswan with -static -fPIE is invalid and will fail with an error like
this one:

/br/output/host/opt/ext-toolchain/bin/../lib/gcc/mipsel-ctng-linux-uclibc/4.8.2/../../../../mipsel-ctng-linux-uclibc/bin/ld:
/br/output/host/usr/mipsel-buildroot-linux-uclibc/sysroot/usr/lib/libgmp.a(lt2-add.o):
relocation R_MIPS_HI16 against `__gnu_local_gp' can not be used when
making a shared object; recompile with -fPIC

Fixes:

  http://autobuild.buildroot.net/results/68b/68b2211cc7acfbdfed8d4b161cbdaf1429315017/

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/openswan/openswan.mk

@@ -11,8 +11,9 @@ OPENSWAN_LICENSE_FILES = COPYING LICENSE
 
 OPENSWAN_DEPENDENCIES = host-bison host-flex gmp iproute2
 OPENSWAN_MAKE_OPTS = ARCH=$(BR2_ARCH) CC="$(TARGET_CC)" \
-	USERCOMPILE="$(TARGET_CFLAGS) -fPIE" INC_USRLOCAL=/usr \
-	USE_KLIPS=false USE_MAST=false USE_NM=false
+	USERCOMPILE="$(TARGET_CFLAGS) $(if $(BR2_STATIC_LIBS),,-fPIE)" \
+	USERLINK="$(TARGET_LDFLAGS) $(if $(BR2_STATIC_LIBS),,-fPIE)" \
+	INC_USRLOCAL=/usr USE_KLIPS=false USE_MAST=false USE_NM=false
 
 ifeq ($(BR2_PACKAGE_LIBCURL),y)
 	OPENSWAN_DEPENDENCIES += libcurl