pixiewps: fix static linking with uclibc-ng

Fixes following linking error with uClibc-ng:
/home/peko/autobuild/instance-0/output/host/lib/gcc/powerpc-buildroot-linux-uclibc/7.3.0/libgcc.a(unwind-dw2-fde-dip.o):
In function `_Unwind_Find_FDE':
/home/peko/autobuild/instance-0/output/build/host-gcc-final-7.3.0/build/powerpc-buildroot-linux-uclibc/libgcc/../../../libgcc/unwind-dw2-fde-dip.c:469:
undefined reference to `dl_iterate_phdr'
collect2: error: ld returned 1 exit status

Since uClibc-ng 1.0.18 a circular dependency between libc and libgcc
exist, when static linking is used. It can be resolved by the compiler
when -static is correctly passed in the linking step.

So use TARGET_CONFIGURE_OPTS to pass CC as well as LDFLAGS to make

Fixes:
 - http://autobuild.buildroot.net/results/d9f0311538c8db1196839e36af3f6ef4e403be2b

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/pixiewps/pixiewps.mk

@@ -10,7 +10,7 @@ PIXIEWPS_LICENSE = GPL-3.0+
 PIXIEWPS_LICENSE_FILES = LICENSE.md
 
 define PIXIEWPS_BUILD_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) CC=$(TARGET_CC) -C $(@D)
+	$(TARGET_MAKE_ENV) $(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D)
 endef
 
 define PIXIEWPS_INSTALL_TARGET_CMDS