opam: adhere to zsh naming convention

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
opam: capture required libs as resources

Closes #26066.
Closes #29508.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
Update mpich to 3.1.2

Update mpich stable branch from 3.1.1 to 3.1.2
mpich2: add 3.1.2 bottle.