Renaming _openssl files to _impl

Since we no longer have NSS implementations, we rename all the _openssl
specific implementations to _impl to align with the rest of the code
base.

[email protected]
[email protected], [email protected]
BUG=604728

Review URL: https://codereview.chromium.org/1921563003

Cr-Commit-Position: refs/heads/master@{#389776}
diff --git a/crypto/BUILD.gn b/crypto/BUILD.gn
index d42065f..5c5ac48 100644
--- a/crypto/BUILD.gn
+++ b/crypto/BUILD.gn
@@ -25,8 +25,8 @@
     "ec_private_key.h",
     "ec_signature_creator.cc",
     "ec_signature_creator.h",
+    "ec_signature_creator_impl.cc",
     "ec_signature_creator_impl.h",
-    "ec_signature_creator_openssl.cc",
     "encryptor.cc",
     "encryptor.h",
     "hkdf.cc",