Use portable format specifiers: Clint advice & other.

- Modify Clint advice to reflect preference for fixed sized macros.
- Cleanup comment to eliminate referecen to "%ld".

clint.py

@@ -1428,7 +1428,7 @@ def CheckForNonStandardConstructs(filename, clean_lines, linenum,
   not standard C++.  Warning about these in lint is one way to ease the
   transition to new compilers.
   - put storage class first (e.g. "static const" instead of "const static").
-  - "%lld" instead of %qd" in printf-type functions.
+  - "%" PRId64 instead of %qd" in printf-type functions.
   - "%1$d" is non-standard in printf-type functions.
   - "\%" is an undefined character escape sequence.
   - text after #endif is not allowed.
@@ -1454,7 +1454,7 @@ def CheckForNonStandardConstructs(filename, clean_lines, linenum,
 
   if Search(r'printf\s*\(.*".*%[-+ ]?\d*q', line):
     error(filename, linenum, 'runtime/printf_format', 3,
-          '%q in format strings is deprecated.  Use %ll instead.')
+          '"%q" in format strings is deprecated.  Use "%" PRId64 instead.')
 
   if Search(r'printf\s*\(.*".*%\d+\$', line):
     error(filename, linenum, 'runtime/printf_format', 2,

src/screen.c

@@ -2232,7 +2232,7 @@ win_line (
   int row;                              /* row in the window, excl w_winrow */
   int screen_row;                       /* row on the screen, incl w_winrow */
 
-  char_u extra[18];                     /* "%ld" and 'fdc' must fit in here */
+  char_u extra[18];                     /* line number and 'fdc' must fit in here */
   int n_extra = 0;                      /* number of extra chars */
   char_u      *p_extra = NULL;          /* string of extra chars, plus NUL */
   int c_extra = NUL;                    /* extra chars, all the same */