rust-common.inc: +v7 implies +neon

If we don't support neon, then (at least on armv7) we must explicitly
throw -neon.  Additionally, this must occur after the "+v7" to have an
effect.

recipes-devtools/rust/rust-common.inc

@@ -24,9 +24,6 @@ def llvm_features_from_tune(d):
     if 'vfpv2' in feat or 'vfp' in feat:
         f.append("+vfp2")
 
-    if 'neon' in feat:
-        f.append("+neon")
-
     if 'mips32' in feat:
         f.append("+mips32")
 
@@ -36,6 +33,11 @@ def llvm_features_from_tune(d):
     if target_is_armv7(d):
         f.append('+v7')
 
+    if 'neon' in feat:
+        f.append("+neon")
+    else:
+        f.append("-neon")
+
     if ('armv6' in mach_overrides) or ('armv6' in feat):
         f.append("+v6")
     if 'armv5te' in feat: