Bug 1687433 - Don't build libffi assembly with -no-integrated-as. r=firefox-build-system-reviewers,mhentges

Back when the flag was added, the libffi source code didn't build for
ARM with the clang integrated assembler. That has been fixed with the
upgrade to libffi v3.3 in bug 1659906, so we can use the integrated
assembler now.

Differential Revision: https://phabricator.services.mozilla.com/D102261

config/external/ffi/moz.build

@@ -119,8 +119,6 @@ else:
 
     else:
         ffi_srcs = ("ffi.c", "sysv.S")
-        if CONFIG["FFI_TARGET"] == "ARM" and CONFIG["CC_TYPE"] == "clang":
-            ASFLAGS += ["-no-integrated-as"]
 
     if CONFIG["FFI_TARGET"] in ("X86_WIN32", "X86_DARWIN") and CONFIG["CC_TYPE"] in (
         "gcc",