Move ev_root_ca_metadata to read-only data segment

Due to a quirk in VC++ it is easy to accidentally prevent a const global
array from being placed in the read-only data segment. This change
removes a should-be-harmless 'const' keyword to work around this quirk
and move ~6,800 bytes to the .rdata (read-only) data segment.

VC++ bug is filed here:
https://connect.microsoft.com/VisualStudio/feedback/details/3117602

Other instances of this quirk are also being worked around.

BUG=677351

Review-Url: https://codereview.chromium.org/2607183002
Cr-Commit-Position: refs/heads/master@{#440977}

net/cert/ev_root_ca_metadata.cc

@@ -41,7 +41,7 @@ struct EVMetadata {
   SHA1HashValue fingerprint;
 
   // The EV policy OIDs of the root CA.
-  const char policy_oids[kMaxOIDsPerCA][kMaxOIDLength];
+  char policy_oids[kMaxOIDsPerCA][kMaxOIDLength];
 };
 
 static const EVMetadata ev_root_ca_metadata[] = {