BuildSystem: Automatically delete libtool files

Half of the ports had a manual post_install step to delete libtool files
this is now done automatically and there is no need for it!

Libtool files have to be deleted as libtool doesn't work while
cross-compiling (at least out of the box)

ports/freetype/build.sh

@@ -5,12 +5,6 @@ VERSION='2.13.3'
 DOWNLOAD_URL="https://download.savannah.gnu.org/releases/freetype/freetype-$VERSION.tar.gz#5c3a8e78f7b24c20b25b54ee575d6daa40007a5f4eea2845861c3409b3021747"
 DEPENDENCIES=('zlib' 'libpng')
 CONFIG_SUB=('builds/unix/config.sub')
-
 CONFIGURE_OPTIONS=(
 	'lt_cv_deplibs_check_method=pass_all'
 )
-
-post_install() {
-	# remove libtool file
-	rm -f $BANAN_SYSROOT/usr/lib/libfreetype.la
-}