apple: Convert GN libs lists to frameworks in //crypto.

GN recently added support for Apple frameworks to link, rather than
overloading the libs lists. This pulls .frameworks out of the libs
lists, so that GN can stop supporting .frameworks in libs in the
future.

Bug: 1052560
Change-Id: I7fae5914dab70e9eb95b25dd15ada370522d3bbe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2274825Reviewed-by: David Benjamin <davidben@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#784202}

crypto/BUILD.gn

@@ -84,7 +84,7 @@ component("crypto") {
       "mock_apple_keychain.h",
     ]
   } else {
-    libs = [
+    frameworks = [
       "CoreFoundation.framework",
       "Security.framework",
     ]