Support building with BoringSSL

BoringSSL is Google's cleanup of OpenSSL and an attempt to unify
Chromium, Android and internal codebases around a single OpenSSL.

As part of moving Android to BoringSSL, the wpa_supplicant maintainers
in Android requested that I upstream the change. I've worked to reduce
the size of the patch a lot but I'm afraid that it still contains a
number of #ifdefs.

[1] https://www.imperialviolet.org/2014/06/20/boringssl.html

Signed-off-by: Adam Langley <agl@chromium.org>

src/eap_common/eap_pwd_common.c

@@ -106,9 +106,11 @@ int compute_password_element(EAP_PWD_group *grp, u16 num,
         case 21:
 		nid = NID_secp521r1;
 		break;
+#ifndef OPENSSL_IS_BORINGSSL
         case 25:
 		nid = NID_X9_62_prime192v1;
 		break;
+#endif /* OPENSSL_IS_BORINGSSL */
         case 26:
 		nid = NID_secp224r1;
 		break;