Compiling with the flang compiler

[Neil Carlson]

This issue tracks the status of compiling petaca using the flang compiler, which is currently not working.

You should use the flang branch, which contains additions, workarounds, etc. for the compiler. I periodically rebase it onto the master branch (bad practice, I know -- sorry).

[Neil Carlson]

Using the March 2019 binary release, these are the failing tests:

The following tests FAILED:
	  4 - any_vector (Failed)
	  5 - any_matrix (Failed)
	  6 - parameter_list (SEGFAULT)
	  7 - parameter_list_json (Failed)

Workarounds for several serious compiler bugs were required to get to this point, including:

• flang-compiler/flang#244 -- intrinsic assignment of types with class(*) component does not work.
• flang-compiler/flang#721 -- move_alloc does not work with character variables
• flang-compiler/flang#722 -- allocate with MOLD= does not work

Other compiler bugs with no apparent workaround as of yet are:

• flang-compiler/flang#713
• flang-compiler/flang#714
  These involve allocation of a class(*) variable and/or array to a character type. The compiler is severely broken when it comes to this.