build: silence mingw fpic warning spew

configure.ac

@@ -345,7 +345,6 @@ fi
 if test x$use_hardening != xno; then
   AX_CHECK_COMPILE_FLAG([-Wstack-protector],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -Wstack-protector"])
   AX_CHECK_COMPILE_FLAG([-fstack-protector-all],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -fstack-protector-all"])
-  AX_CHECK_COMPILE_FLAG([-fPIE],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -fPIE"])
 
   AX_CHECK_PREPROC_FLAG([-D_FORTIFY_SOURCE=2],[
     AX_CHECK_PREPROC_FLAG([-U_FORTIFY_SOURCE],[
@@ -360,7 +359,8 @@ if test x$use_hardening != xno; then
   AX_CHECK_LINK_FLAG([[-Wl,-z,now]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -Wl,-z,now"])
 
   if test x$TARGET_OS != xwindows; then
-    # -pie will link successfully with MinGW, but it's unsupported and leads to undeterministic binaries
+    # All windows code is PIC, forcing it on just adds useless compile warnings
+    AX_CHECK_COMPILE_FLAG([-fPIE],[HARDENED_CXXFLAGS="$HARDENED_CXXFLAGS -fPIE"])
     AX_CHECK_LINK_FLAG([[-pie]], [HARDENED_LDFLAGS="$HARDENED_LDFLAGS -pie"])
   fi