Assume the 4th component is always mach_comp and the 5th always testmods

[billsacks]

This removes some generality - specifically, it removes the ability to
specify a search string like:

name.grid.compset.testmods

However, the smarts that were trying to determine if a component was the
testmods seemed overly restrictive, and were stopping it from finding
some matches. There were two problems with the previous code:

(1) It assumed that there is exactly one '-' in the testmods; this is
usually the case, but not always

(2) It assumed that it could find the testmods directory under the
current directory. This was an issue e.g. for CISM, where we use
some CLM testmods