[flang] Compile and install the predefined module files.

[flang] Compile and install the predefined module files.

Change the CMakeFile.txt in tools/f18 to build the predefined modules with the just-built compiler. The mod files are created in the new "include" subdirectory of the binary target directory.  The mod files are installed to ${CMAKE_INSTALL_PREFIX}/include.

The f18 driver is already installed in ${CMAKE_INSTALL_PREFIX}/bin.  This change change the location of the f18 binary build to a sibling directory of "include" called "bin" instead of at the top level of the binary destination directory. This change is in anticipation of changing the driver to find the include directory using a path relative to the location of f18.

Update the test scripts to find f18 in the bin subdirectory.

Remove the simple predefined module tests from test/semantics because they are compiled as part of the build and don't need to be recompiled as part of a test.

Original-commit: flang-compiler/f18@7811ccecdc065e7e6eb004c8eaefc245f642aea3
Reviewed-on: https://github.com/flang-compiler/f18/pull/526