MangoHud: fix vulkan layer on musl

OpenGL Overlay is still broken

srcpkgs/MangoHud/files/musl.patch

@@ -0,0 +1,22 @@
+--- src/meson.build	2021-06-11 22:12:53.000000000 +0200
++++ -	2021-06-14 23:32:49.677413454 +0200
+@@ -3,16 +3,16 @@
+ # Needs prefix for configure_file()
+ if get_option('append_libdir_mangohud')
+   libdir_mangohud = join_paths(get_option('libdir'), 'mangohud')
+-  ld_libdir_mangohud = get_option('prefix') + '/\$LIB/mangohud/'
++  ld_libdir_mangohud = join_paths(get_option('prefix') ,get_option('libdir'), 'mangohud')
+ else
+   libdir_mangohud = get_option('libdir')
+-  ld_libdir_mangohud = get_option('prefix') + '/\$LIB/'
++  ld_libdir_mangohud = join_paths(get_option('prefix') ,get_option('libdir'))
+ endif
+ 
+ # For build.sh
+ if get_option('ld_libdir_prefix')
+   # FIXME derive from libdir
+-  ld_libdir_mangohud = get_option('prefix') + '/lib/mangohud/\$LIB/'
++  ld_libdir_mangohud = get_option('prefix') + '/lib/mangohud/lib'
+ endif
+ 
+ conf_data = configuration_data()

srcpkgs/MangoHud/template

@@ -1,7 +1,7 @@
 # Template file for 'MangoHud'
 pkgname=MangoHud
 version=0.6.3
-revision=1
+revision=2
 wrksrc="MangoHud-v${version}"
 build_style=meson
 configure_args="-Duse_system_vulkan=enabled -Dwith_xnvctrl=disabled
@@ -15,6 +15,12 @@ homepage="https://github.com/flightlessmango/MangoHud"
 distfiles="https://github.com/flightlessmango/MangoHud/releases/download/v${version}/MangoHud-v${version}-Source-DFSG.tar.xz"
 checksum=c0d27e1f3ab1fce99ea1cfb48afe97dcad1c78dfc72c9ab9dbcb0ce2366909ec
 
+post_patch() {
+	if [ "$XBPS_TARGET_LIBC" = "musl" ]; then
+		patch -Np0 -i ${FILESDIR}/musl.patch
+	fi
+}
+
 post_install() {
 	vlicense LICENSE
 }