Revert "Add function to catenate n copies of a string"

COMPHELPER_DLLPUBLIC of an inline function is wrong. Nevermind that I just
followed the example of the preceding functions.

And it is too bikeshedding-inducing anyway to use recursion.

This wasn't used anywahere yet anyway in committed code, just locally in a
tree of mine. Will add a local copy there.

This reverts commit ee0d7d4c52fe93ef2ac73d403f61b642f1ae2716.