msmtp: remove unused dependencies

[ryandesign (Ryan Carsten Schmidt)]

msmtp declares library dependencies on libgcrypt and libgpg-error but does not actually link with those libraries:

$ port -v installed msmtp
The following ports are currently installed:
  msmtp @1.4.32_1+universal (active) platform='darwin 13' archs='i386 x86_64'
$ port deps msmtp
Full Name: msmtp @1.4.32_1+universal
Build Dependencies:   pkgconfig
Library Dependencies: gettext, gnutls, libgcrypt, libgpg-error, libgsasl, libiconv, libtasn1
$ otool -L /opt/local/bin/msmtp
/opt/local/bin/msmtp:
	/opt/local/lib/libintl.8.dylib (compatibility version 10.0.0, current version 10.2.0)
	/opt/local/lib/libgnutls.28.dylib (compatibility version 67.0.0, current version 67.0.0)
	/opt/local/lib/libgsasl.7.dylib (compatibility version 17.0.0, current version 17.6.0)
	/opt/local/lib/libidn.11.dylib (compatibility version 18.0.0, current version 18.9.0)
	/opt/local/lib/libgnome-keyring.0.dylib (compatibility version 3.0.0, current version 3.0.0)
	/opt/local/lib/libglib-2.0.0.dylib (compatibility version 4001.0.0, current version 4001.0.0)
	/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 855.14.0)
	/System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 55471.14.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)

These dependencies were added way back in r15622. Perhaps msmtp at one point linked with those dependencies due to overlinking, but current MacPorts doesn't do that anymore. Can the unused dependencies be removed? It seems to build fine even if I deactivate them first.

Meanwhile, perhaps dependencies on libidn, gnome-keyring, and glib2 need to be added, since they are linked with.

[neverpanic (Clemens Lang)]

Patch available in #49927.

[neverpanic (Clemens Lang)]

Committed in r143327, see #49927.