tests: avoid DOS line endings in PSK file

Using FILE * APIs for writing the PSK file results in translation from
UNIX to DOS line endings on Windows. When the crypto PSK code later
loads the credentials the stray \r will result in failure to load the
PSK credentials into GNUTLS.

Rather than switching the FILE* APIs to open in binary format, just
switch to the more concise g_file_set_contents API.

Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

tests/unit/crypto-tls-psk-helpers.c

@@ -27,15 +27,14 @@
 static void
 test_tls_psk_init_common(const char *pskfile, const char *user, const char *key)
 {
-    FILE *fp;
+    g_autoptr(GError) gerr = NULL;
+    g_autofree char *line = g_strdup_printf("%s:%s\n", user, key);
 
-    fp = fopen(pskfile, "w");
-    if (fp == NULL) {
-        g_critical("Failed to create pskfile %s: %s", pskfile, strerror(errno));
+    g_file_set_contents(pskfile, line, strlen(line), &gerr);
+    if (gerr != NULL) {
+        g_critical("Failed to create pskfile %s: %s", pskfile, gerr->message);
         abort();
     }
-    fprintf(fp, "%s:%s\n", user, key);
-    fclose(fp);
 }
 
 void test_tls_psk_init(const char *pskfile)