…ne continuation
Allow preprocessing directives to appear between a source line and its
continuation, including conditional compilation directives (#if, #ifdef,
&c.).
Fixes https://github.com/llvm/llvm-project/issues/95476.
Some applications like to use a CPP-style #include directive to pull in
a common list of arguments, dummy arguments, or COMMON block variables
after a free-form & line continuation marker. This works naturally with
compilers that run an actual cpp pass over the input before doing
anything specific to Fortran, but it's a case that I missed with this
integrated preprocessor.
