modpost: expand pattern matching to support substring matches

Currently the match() function supports a leading * to match any
prefix and a trailing * to match any suffix.  However there currently
is not a combination of both that can be used to target matches of
whole families of functions that share a common substring.

Here we expand the *foo and foo* match to also support *foo* with
the goal of targeting compiler generated symbol names that contain
strings like ".constprop." and ".isra."

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>