larsch

# Function for setting up precompiled headers. Usage:
#
#   add_library/executable(target
#       pchheader.c pchheader.cpp pchheader.h)
#
#   add_precompiled_header(target pchheader.h
#       [FORCEINCLUDE]
#       [SOURCE_C pchheader.c]
#       [SOURCE_CXX pchheader.cpp])
#