Bug 1580234 - Disable the custom linker when mozjemalloc is disabled. r=froydnj

Long term, we want to remove the custom linker (bug 1291377) but without
more effort than where we're at with bug 1598196, it would break using
mozjemalloc.

However, some builds using sanitizers don't use mozjemalloc already,
and in their case, we can already disable the custom linker.

Differential Revision: https://phabricator.services.mozilla.com/D54078

--HG--
extra : moz-landing-system : lando

old-configure.in

@@ -581,7 +581,7 @@ case "$target" in
     ;;
 
 *-android*|*-linuxandroid*)
-    if test "$COMPILE_ENVIRONMENT"; then
+    if test "$COMPILE_ENVIRONMENT" -a -n "$MOZ_MEMORY"; then
         MOZ_LINKER=1
     fi