external/boringssl: Sync to aa2485.

This includes the following changes:

https://boringssl.googlesource.com/boringssl/+log/171b5403ee767fa0f3aecd377867db6533c3eb8f..aa24851515d6280aa1d6a8b1548fe74691df3136

Bug: 29744850
Change-Id: Id4e4a9e7a19c2f0badbaead2c39a51037ba182ed
diff --git a/src/crypto/crypto.c b/src/crypto/crypto.c
index c9f2bc8..2443126 100644
--- a/src/crypto/crypto.c
+++ b/src/crypto/crypto.c
@@ -153,6 +153,10 @@
 
 void ENGINE_load_builtin_engines(void) {}
 
+int ENGINE_register_all_complete(void) {
+  return 1;
+}
+
 void OPENSSL_load_builtin_modules(void) {}
 
 int FIPS_mode(void) { return 0; }