All: under mingw32+msys: fix an issue when using Cmake version >= 2.8.5 which uses by default a response file.
This response file is not expanded under mingw3 2 (mingw/gcc bug?), and the list of include paths, found in this file, is not taken in account.
Now, under mingw32+msys, when not cross-compiling, the response file is disabled.
Cvpcb, Pcbnew: fix a list of libs  which should be added only when cross-compiling:
Previously, they were always added, which creates an issue with mingw/msy/ gcc  2.8.
Now they are added only when cross-compiling (this issue was noticeable only with msys+mingw version  2.8)