CryptoPkg: Declare PcdEcEnabled in Library consuming OpensslLib

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3679
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3828

Tls/Base/Pei/Smm/RuntimeCryptLib.inf will use OpensslLib,
and the opensslconf.h in openssllib will use PcdEcEnabled,
but it is not declared in the inf file now,
it will cause warnings in some compilers.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Yi Li <yi1.li@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

CryptoPkg/Library/BaseCryptLib/UnitTestHostBaseCryptLib.inf

@@ -72,6 +72,9 @@
   DebugLib
   OpensslLib
 
+[FixedPcd]
+  gEfiCryptoPkgTokenSpaceGuid.PcdEcEnabled
+
 #
 # Remove these [BuildOptions] after this library is cleaned up
 #