alpine: Require curl-ca-bundle with +ssl.

Some server certificates aren't based on root CAs included with the OS
(at least for some OS versions).  Installing curl-ca-bundle typically
provides the needed root CAs, and isn't very expensive.  Since other
common installs already depend on curl-ca-bundle, it's likely that
Alpine has been opportunistically getting it in most cases.

Theoretically, this change should get a revbump to ensure that the
dependency is included.  But since most installations probably already
have curl-ca-bundle installed, it's not really worth a rebuild to fix
the rare cases.

Also removes redundant "platforms darwin" (to get rid of a lint
warning).

TESTED:
Correctly shows dependency iff +ssl.
Active curl-ca-bundle fixes access to at least one server.

Author: fhgwright

mail/alpine/Portfile

@@ -8,7 +8,6 @@ revision            0
 categories          mail
 license             Apache-2
 maintainers         netpurgatory.com:john gmail.com:jerryyhom openmaintainer
-platforms           darwin
 
 homepage            https://alpineapp.email/
 description         alpine - a Program for Internet News and Email
@@ -80,6 +79,8 @@ variant ldap description {LDAP support} {
 
 variant ssl description {OpenSSL support} {
     depends_lib-append      path:lib/libssl.dylib:openssl
+    # Some server certificates may require root CAs not provided by the OS
+    depends_run-append      port:curl-ca-bundle
     configure.args-delete   --without-ssl
     build.env-delete        SSLTYPE=none
 }