vim-patch:9.0.2180: POSIX function name in exarg causes issues (#28308)

Problem:  POSIX function name in exarg struct causes issues
          on OpenVMS
Solution: Rename getline member in exarg struct to ea_getline,
          remove isinf() workaround for VMS

There are compilers that do not treat well POSIX functions - like
getline - usage in the structs.

Older VMS compilers could digest this... but the newer OpenVMS compilers
( like VSI C x86-64 X7.4-843 (GEM 50XB9) ) cannot deal with these
structs. This could be limited to getline() that is defined via
getdelim() and might not affect all POSIX functions in general - but
avoiding POSIX function names usage in the structs is a "safe side"
practice without compromising the functionality or the code readability.

The previous OpenVMS X86 port used a workaround limiting the compiler
capabilities using __CRTL_VER_OVERRIDE=80400000
In order to make the OpenVMS port future proof, this pull request
proposes a possible solution.

closes: vim/vim#13704

6fdb628082

Co-authored-by: Zoltan Arpadffy <zoltan.arpadffy@gmail.com>

src/nvim/ex_cmds_defs.h

@@ -167,8 +167,8 @@ struct exarg {
   int bad_char;                 ///< BAD_KEEP, BAD_DROP or replacement byte
   int useridx;                  ///< user command index
   char *errmsg;                 ///< returned error message
-  LineGetter getline;           ///< Function used to get the next line
-  void *cookie;                 ///< argument for getline()
+  LineGetter ea_getline;        ///< function used to get the next line
+  void *cookie;                 ///< argument for ea_getline()
   cstack_T *cstack;             ///< condition stack for ":if" etc.
 };