gtk.cfg: Remove pure annotation from g_str_has_prefix/suffix

g_str_has_prefix and g_str_has_suffix are not technically pure
because they can log to the console if a precondition fails.

This partially reverts commit 7cc7c0b.

Author: correctmost

cfg/gtk.cfg

@@ -5221,7 +5221,6 @@
   <!-- gboolean g_str_has_prefix (const gchar* str, const gchar* prefix); -->
   <!-- gboolean g_str_has_suffix (const gchar* str, const gchar* prefix); -->
   <function name="g_str_has_prefix,g_str_has_suffix">
-    <pure/>
     <leak-ignore/>
     <noreturn>false</noreturn>
     <returnValue type="gboolean"/>

test/cfg/gtk.c

@@ -59,8 +59,6 @@ void validCode(int argInt, GHashTableIter * hash_table_iter, GHashTable * hash_t
     g_string_free(pGStr1, TRUE);
 
     gchar * pGchar1 = g_strconcat("a", "b", NULL);
-    g_assert_true(g_str_has_prefix(pGchar1, "a"));
-    g_assert_true(g_str_has_suffix(pGchar1, "b"));
     printf("%s", pGchar1);
     g_free(pGchar1);