Bug 1420092 - Enable mozjemalloc by default on 32-bit OSX. r=njn

Hopefully, the bug we worked around by disabling jemalloc on 32-bit OSX
is gone. We're not shipping 32-bit binaries for OSX anyways.

--HG--
extra : rebase_source : bfe765977dedf1949da4d5919032cadfb4675f1f

build/moz.configure/memory.configure

@@ -22,16 +22,12 @@ def jemalloc(value, target, build_project, c_compiler):
     if build_project == 'js':
         return True
 
-    if target.kernel == 'Darwin' and target.cpu == 'x86_64':
-        # Don't enable by default on 32-bits OSX. See bug 702250.
+    if target.kernel in ('Darwin', 'Linux'):
         return True
 
     if target.kernel == 'WINNT' and c_compiler.type in ('msvc', 'clang-cl'):
         return True
 
-    if target.kernel == 'Linux':
-        return True
-
     if value and target.kernel not in ('WINNT', 'Linux', 'Darwin', 'kFreeBSD',
                                        'FreeBSD', 'NetBSD'):
         die('--enable-jemalloc is not supported on %s', target.kernel)