rustc_codegen_ssa: Don't skip target-features after crt-static

The current behaviour introduced by commit
a50a3b8e31 would discard any
target features specified after crt-static (the only member of
RUSTC_SPECIFIC_FEATURES). This is because it returned instead of
continuing processing the next flag.

Signed-off-by: Jens Reidel <adrian@travitia.xyz>
(cherry picked from commit 664d742933)

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -176,14 +176,14 @@ fn parse_rust_feature_flag<'a>(
         if let Some(base_feature) = feature.strip_prefix('+') {
             // Skip features that are not target features, but rustc features.
             if RUSTC_SPECIFIC_FEATURES.contains(&base_feature) {
-                return;
+                continue;
             }
 
             callback(base_feature, sess.target.implied_target_features(base_feature), true)
         } else if let Some(base_feature) = feature.strip_prefix('-') {
             // Skip features that are not target features, but rustc features.
             if RUSTC_SPECIFIC_FEATURES.contains(&base_feature) {
-                return;
+                continue;
             }
 
             // If `f1` implies `f2`, then `!f2` implies `!f1` -- this is standard logical