libbb: introduce last_char_is_dir_sep()

Add a convenience function to determine if the last character of
a string is a directory separator.

Adds 16-32 bytes.

1 files changed, 2 insertions, 2 deletions

diff --git a/libbb/concat_path_file.c b/libbb/concat_path_file.c
index 81c7481ca..3afb0e3a4 100644
--- a/libbb/concat_path_file.c
+++ b/libbb/concat_path_file.c
@@ -22,8 +22,8 @@ char* FAST_FUNC concat_path_file(const char *path, const char *filename)
         if (!path)
                 path = "";
 #if ENABLE_PLATFORM_MINGW32
-        lc = last_char_is(path, '/') ?: last_char_is(path, '\\');
-        while (*filename == '/' || *filename == '\\')
+        lc = last_char_is_dir_sep(path);
+        while (is_dir_sep(*filename))
                 filename++;
 #else
         lc = last_char_is(path, '/');