IBM rebranded its VisualAge compiler to XL starting at version 8.0. We
use the compiler id "XL" for newer versions and "VisualAge" for older
versions. We now also recognize the "z/OS" compiler, which is distinct
from XL.
This teaches CMake to detect implicit link information for C, C++, and
Fortran compilers. We detect the implicit linker search directories and
implicit linker options for UNIX-like environments using verbose output
from compiler front-ends. We store results in new variables called
CMAKE_<LANG>_IMPLICIT_LINK_LIBRARIES
CMAKE_<LANG>_IMPLICIT_LINK_DIRECTORIES
The implicit libraries can contain linker flags as well as library
names.
Brad King