maint: accommodate gcc's -Wstrict-overflow option

* src/factor.c (factor_using_pollard_rho): Change type of "i"
to unsigned to avoid warning from gcc's -Wstrict-overflow.
* src/expr.c: Use an unsigned intermediate.
* src/dircolors.c (main): Reorder operations to avoid the risk of
pointer overflow.
* src/tr.c (squeeze_filter): Change NOT_A_CHAR from an anonymous
"enum" to an "int", to avoid this warning:
tr.c:1624:10: error: assuming signed overflow does not occur when
  simplifying conditional to constant [-Werror=strict-overflow]
* src/pr.c (main): Make index "i" unsigned.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/dircolors.c b/src/dircolors.c
index d1962eae9..9aaa87fc2 100644
--- a/src/dircolors.c
+++ b/src/dircolors.c
@@ -456,7 +456,7 @@ to select a shell syntax are mutually exclusive"));
   if (print_database)
     {
       char const *p = G_line;
-      while (p < G_line + sizeof G_line)
+      while (p - G_line < sizeof G_line)
         {
           puts (p);
           p += strlen (p) + 1;