Build argp object files with -fPIC.

The argp bundled dependency is linked to the libwvutils.so shared library.
MIPS will refuce to link a non-PIC library with a shared one.

We fix this problem by building the argp source files using -fPIC since
the libargp static library will only be used to link to libwvutils.so
as instructed by the following rule in the root Makefile:

ifeq ($(USE_WVSTREAMS_ARGP),1)
  utils/wvargs.o-CPPFLAGS += -Iargp
  libwvutils.so-LIBS += -Largp -largp

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Index: argp/Makefile.in
===================================================================
--- argp/Makefile.in.old
+++ argp/Makefile.in
@@ -137,7 +137,7 @@ AUTOMAKE = @AUTOMAKE@
 AWK = @AWK@
 CC = @CC@
 CCDEPMODE = @CCDEPMODE@
-CFLAGS = @CFLAGS@
+CFLAGS = @CFLAGS@ -fPIC
 CPP = @CPP@
 CPPFLAGS = @CPPFLAGS@
 CYGPATH_W = @CYGPATH_W@
