Now that semantics is working, the standard -fsyntax-only option of
GNU and Clang should be used as the name of the option that causes
f18 to just run the front-end. Support both options in f18, silently
accepting the old option as a synonym for the new one (as
preferred by the code owner), and replace all instances of the
old -fparse-only option with -fsyntax-only throughout the source base.
Differential Revision: https://reviews.llvm.org/D95887
Implement rest of DATA statement semantics and conversion of
DATA statement initializations into static initializers of
objects in their symbol table entries.
Reviewed By: tskeith, PeteSteinfeld
Differential Revision: https://reviews.llvm.org/D82207
