Fix -march= flag autodetection.

Bug: https://gcc.gnu.org/PR85658
diff --git a/gcc/config/arm/parsecpu.awk b/gcc/config/arm/parsecpu.awk
index 56c762b3b..1135f735b 100644
--- a/gcc/config/arm/parsecpu.awk
+++ b/gcc/config/arm/parsecpu.awk
@@ -485,7 +485,7 @@ function check_fpu (name) {
 function check_arch (name) {
     exts = split (name, extensions, "+")
 
-    if (! extensions[1] in arch_isa) {
+    if (! (extensions[1] in arch_isa)) {
 	return "error"
     }