Several module files in .../llvm-project/flang/module check for the
existence of the macro "__x86_64__" to conditionally compile Fortran
code. Unfortunately, this macro was not being defined anywhere. This
patch fixes that for compilations targeting 64 bit x86 machines.
I made the following changes --
-- Removed the test for 32 bit X86 targets. The rest of the compiler and
runtime do not support X86 32 bits.
-- Added predefined macros to define "__x86_64__" and "__x86__64" to
be 1 when the target architecture is 64 bit x86 and the "-cpp" option
is on the command line.
-- Changed the cmake file for creating the Fortran module files to use the
"-cpp" option so that the macro "__x86_64__" will be defined when building
the module files.
-- Added a test.
Differential Revision: https://reviews.llvm.org/D135810