configure: Run SHFLAGS through ldflags_filter()

These flags are as linker-specific as other LDFLAGS and thus
need to be translated to the correct linker syntax.
Signed-off-by: Diego Biurrun <diego@biurrun.de>

configure

@@ -3892,7 +3892,7 @@ LD_PATH=$LD_PATH
 DLLTOOL=$dlltool
 LDFLAGS=$LDFLAGS
 LDFLAGS-avserver=$AVSERVERLDFLAGS
-SHFLAGS=$SHFLAGS
+SHFLAGS=$(echo $($ldflags_filter $SHFLAGS))
 YASMFLAGS=$YASMFLAGS
 BUILDSUF=$build_suffix
 FULLNAME=$FULLNAME