52924a2d72
Add a new Cygwin toolchain that just goes through the motions to initialize the Generic_GCC base properly. This allows removing some old, almost certainly wrong hard-coded paths from Lex/InitHeaderSearch.cpp. MSYS2 (GCC triple (arch)-pc-msys) is a fork of Cygwin (GCC triple (arch)-pc-cygwin), and this driver can be used for either. Add a simple test for this driver.