misc/ios: quote paths

The paths may contain spaces. Quote them.

Change-Id: I1f67085a1e7c40f60282c2fea7104fb44a01e310
Reviewed-on: https://go-review.googlesource.com/c/go/+/254739
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/misc/ios/clangwrap.sh b/misc/ios/clangwrap.sh
index 5fdbb6d..1d6dee2 100755
--- a/misc/ios/clangwrap.sh
+++ b/misc/ios/clangwrap.sh
@@ -15,4 +15,4 @@
 	exit 1
 fi
 
-exec $CLANG -arch $CLANGARCH -isysroot $SDK_PATH -mios-version-min=10.0 "$@"
+exec "$CLANG" -arch $CLANGARCH -isysroot "$SDK_PATH" -mios-version-min=10.0 "$@"