maint: prefer STREQ_LEN and STRPREFIX over strncmp in all cases

* cfg.mk (sc_prohibit_strncmp): Improve the search pattern: use
_sc_search_regexp to find all invocations of strncmp except when
used on a macro definition line; just match the function name with
an opening parenthesis.  Before, the expression missed places where
the comparison against 0 was in a subsequent line.
* src/system.h (STRNCMP_LIT): Shorten 'literal' to 'lit' to move
the whole definition of the macro into one line - thus making
sc_prohibit_strncmp pass.
(STRPREFIX): Add space before parenthesis.
* src/du.c (main): Prefer STREQ_LEN over strncmp.
* src/pinky.c (scan_entries): Likewise.
* src/tac.c (tac_seekable): Likewise.
* src/who.c (scan_entries): Likewise.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/du.c b/src/du.c
index 65fc0742f..86827f808 100644
--- a/src/du.c
+++ b/src/du.c
@@ -968,9 +968,9 @@ main (int argc, char **argv)
             {
               /* Ignore "posix-" prefix, for compatibility with ls.  */
               static char const posix_prefix[] = "posix-";
-              while (strncmp (time_style, posix_prefix, sizeof posix_prefix - 1)
-                     == 0)
-                time_style += sizeof posix_prefix - 1;
+              static const size_t prefix_len = sizeof posix_prefix - 1;
+              while (STREQ_LEN (time_style, posix_prefix, prefix_len))
+                time_style += prefix_len;
             }
         }