Add support files for C, C++ and ASM for the IAR toolchain.

The original feature request is at http://www.cmake.org/Bug/view.php?id=10176
Documentation can be found at http://www.iar.com/website1/1.0.1.0/675/1/

Alex
Add regexps for the IAR toolchain to the vendor list.

The IAR compilers produce object files where the plain strings at least
sometimes can't be found, see:

  http://www.cmake.org/Bug/view.php?id=10176#c19598

Alex
Add IAR to the CMakeDetectC(XX)CompilerID.c(pp).in

With the AVR IAR compiler this can't be found, but it works e.g. for the
ARM AVR compiler.

Alex
Merge topic 'AddIARToolchain2' into next

d118b8b Add IAR to the CMakeDetectC(XX)CompilerID.c(pp).in
d33f406 Add regexps for the IAR toolchain to the vendor list.
22fb73a Add support files for C, C++ and ASM for the IAR toolchain.