tree-wide: add global ascii_isdigit() + ascii_isalpha()

We now have a local implementation in string-util-fundamental.c, but
it's useful at a lot of other places, hence let's give it a more
expressive name and share it across the tree.

Follow-up for: 8d9156660d6958c8d63b1d44692968f1b5d33920

1 files changed, 2 insertions, 3 deletions

diff --git a/src/login/logind-seat.c b/src/login/logind-seat.c
index 88ff4ce45e..43c72da11f 100644
--- a/src/login/logind-seat.c
+++ b/src/login/logind-seat.c
@@ -646,9 +646,8 @@ void seat_add_to_gc_queue(Seat *s) {
 
 static bool seat_name_valid_char(char c) {
         return
-                (c >= 'a' && c <= 'z') ||
-                (c >= 'A' && c <= 'Z') ||
-                (c >= '0' && c <= '9') ||
+                ascii_isalpha(c) ||
+                ascii_isdigit(c) ||
                 IN_SET(c, '-', '_');
 }