ident.c: treat $EMAIL as giving user.email identity explicitly
ident.c: treat $EMAIL as giving user.email identity explicitly

The environment variable EMAIL has been honored since 28a94f8 (Fall back
to $EMAIL for missing GIT_AUTHOR_EMAIL and GIT_COMMITTER_EMAIL,
2007-04-28) as the end-user's wish to use the address as the identity.
When we use it, we should say we are explicitly given email by the user.

Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git