ghostscript: build with `make -j1`

There were errors (on CI) when building with `make -j $TERMUX_MAKE_PROCESSES`.

packages/ghostscript/build.sh

@@ -20,3 +20,9 @@ CCAUX=gcc
 termux_step_post_extract_package() {
 	rm -rdf $TERMUX_PKG_SRCDIR/{jpeg,libpng,expat,jasper,freetype,lcms2,tiff,openjpeg}
 }
+
+termux_step_pre_configure() {
+	# Use `make -j1` otherwise build may fail with error
+	# about missing 'arch.h'.
+	TERMUX_MAKE_PROCESSES=1
+}