mozjs38: fix *-musl

Add flags for building with gcc6.3 taken from Arch Linux.
Also use system ffi and icu instead of the shipped versions.

srcpkgs/mozjs38/template

@@ -1,12 +1,12 @@
 # Template file for 'mozjs38'
 pkgname=mozjs38
 version=38.8.0
-revision=1
+revision=2
 wrksrc="mozilla-esr${version%.*.*}"
 build_wrksrc="js/src"
 build_style=gnu-configure
-hostmakedepends="perl python"
-makedepends="nspr-devel zlib-devel"
+hostmakedepends="perl python pkg-config"
+makedepends="icu-devel libffi-devel nspr-devel zlib-devel"
 short_desc="Mozilla JavaScript interpreter and library (38.x series)"
 homepage="http://www.mozilla.org/js/"
 license="MPL-1.1, GPL-2, LGPL-2.1"
@@ -15,9 +15,11 @@ distfiles="https://ftp.mozilla.org/pub/firefox/releases/${version}esr/source/fir
 checksum=9475adcee29d590383c4885bc5f958093791d1db4302d694a5d2766698f59982
 nopie=yes
 
-case "$XBPS_TARGET_MACHINE" in
-	x86_64-musl) broken="https://build.voidlinux.eu/builders/x86_64-musl_builder/builds/2009/steps/shell_3/logs/stdio";;
-esac
+# Flags for gcc6.3 conceived by Arch Linux developers
+CFLAGS="-fpermissive -fno-delete-null-pointer-checks -fno-tree-vrp -fno-strict-aliasing"
+CXXFLAGS="-fpermissive -fno-delete-null-pointer-checks -fno-tree-vrp -fno-strict-aliasing"
+# Use BFD linker to avoid erroneous detection of llvm pr8927 with *-musl
+LDFLAGS="-fuse-ld=bfd"
 
 do_configure() {
 	local _args
@@ -29,7 +31,8 @@ do_configure() {
 	fi
 
 	SHELL=/bin/bash ./configure --prefix=/usr --enable-threadsafe \
-		--with-system-nspr ${_args}
+		--enable-system-ffi --with-system-icu --with-system-nspr \
+		${_args}
 }
 
 post_install() {