Don't set NEON_FUNCTIONAL in the getauxval path.

NEON_FUNCTIONAL is set by default in crypto.c. Chromium calls
|CRYPTO_set_NEON_functional| before |SSL_library_init| and thus the
getauxval path for CPU-feature detection was resetting the functional
flag, even on broken processors.

This change means that, apart from the default, only
|CRYPTO_set_NEON_functional| will change the NEON_FUNCTIONAL flag.

BUG=469511

Change-Id: I3d4dbbd9f4a5e33539f8559f90289e706ad17451
Reviewed-on: https://boringssl-review.googlesource.com/4170
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

crypto/cpu-arm.c

diff --git a/crypto/cpu-arm.c b/crypto/cpu-arm.c
index 8ca60fb..325cd22 100644
--- a/crypto/cpu-arm.c
+++ b/crypto/cpu-arm.c
@@ -168,7 +168,7 @@
   }
 #endif
 
-  OPENSSL_armcap_P |= ARMV7_NEON | ARMV7_NEON_FUNCTIONAL;
+  OPENSSL_armcap_P |= ARMV7_NEON;
 
   if (hwcap & kAES) {
     OPENSSL_armcap_P |= ARMV8_AES;