Bug 588424 - Turn --enable-threadsafe (and JS_THREADSAFE) permanently on. (r=jimb)

configure.in

@@ -9503,7 +9503,7 @@ fi
 # Run the SpiderMonkey 'configure' script.
 dist=$MOZ_BUILD_ROOT/dist
 ac_configure_args="$_SUBDIR_CONFIG_ARGS"
-ac_configure_args="$ac_configure_args --enable-threadsafe"
+ac_configure_args="$ac_configure_args"
 if test "$BUILD_CTYPES"; then
     # Build js-ctypes on the platforms we can.
     ac_configure_args="$ac_configure_args --enable-ctypes"

js/src/configure.in

@@ -4510,15 +4510,6 @@ MOZ_ARG_HEADER(External Packages)
 dnl ========================================================
 dnl = Find the right NSPR to use.
 dnl ========================================================
-MOZ_ARG_WITH_BOOL(system-nspr,
-[  --with-system-nspr      Use an NSPR that is already built and installed.
-                          Use the 'nspr-config' script in the current path,
-                          or look for the script in the directories given with
-                          --with-nspr-exec-prefix or --with-nspr-prefix.
-                          (Those flags are only checked if you specify
-                          --with-system-nspr.)],
-    _USE_SYSTEM_NSPR=1 )
-
 MOZ_ARG_WITH_STRING(nspr-cflags,
 [  --with-nspr-cflags=FLAGS
                           Pass FLAGS to CC when building code that uses NSPR.
@@ -4535,19 +4526,13 @@ MOZ_ARG_WITH_STRING(nspr-libs,
 AC_SUBST(NSPR_CFLAGS)
 AC_SUBST(NSPR_LIBS)
 
-dnl Pass either --with-system-nspr or (--with-nspr-cflags and
-dnl --with-nspr-libs), but not both.
-if test "$_USE_SYSTEM_NSPR" && (test "$NSPR_CFLAGS" -o "$NSPR_LIBS"); then
-    AC_MSG_ERROR([--with-system-nspr and --with-nspr-libs/cflags are mutually exclusive.
-See 'configure --help'.])
-fi
-
-dnl Top-level Mozilla switched to requiring NSPR 4.8.6 (bug 560582), but we don't need it in JS.
-if test -n "$_USE_SYSTEM_NSPR"; then
+dnl Top-level Mozilla switched to requiring NSPR 4.8.6 (bug 560582), but JS only needs NSPR 4.7.
+dnl If not using a provided nspr, use one installed on the system.
+if test -z "$NSPR_CFLAGS" -a -z "$NSPR_LIBS"; then
     MOZ_NATIVE_NSPR=
     AM_PATH_NSPR(4.7.0, [MOZ_NATIVE_NSPR=1])
     if test -z "$MOZ_NATIVE_NSPR"; then
-        AC_MSG_ERROR([--with-system-nspr given, but configure could not find a suitable NSPR.
+        AC_MSG_ERROR([NSPR 4.7.0 or later is required, but configure could not find a suitable NSPR.
 Pass --with-nspr-exec-prefix, --with-nspr-prefix, or --with-nspr-cflags/libs.
 See 'configure --help'.])
     fi
@@ -5835,9 +5820,8 @@ elif test "$OS_ARCH" != "WINNT" -a "$OS_ARCH" != "OS2" -a "$OS_ARCH" != "WINCE";
   AC_DEFINE(UNIX_ASYNC_DNS)
 fi
 
-AC_ARG_ENABLE(threadsafe,
-              [  --enable-threadsafe     Enable support for multiple threads.],
-              [AC_DEFINE(JS_THREADSAFE)],)
+dnl --enable-threadsafe used to be an option, but is forced on since FF4.
+AC_DEFINE(JS_THREADSAFE)
 
 if test "$MOZ_DEBUG"; then
     AC_DEFINE(MOZ_REFLOW_PERF)