Define fgetspent_r if not already defined. (GNU extension, therefore not in musl).

https://git.alpinelinux.org/aports/tree/community/accountsservice/musl-fgetspent_r.patch (copied the function from here).
diff -u b/src/daemon.c b/src/daemon.c
--- b/src/daemon.c
+++ b/src/daemon.c
@@ -32,7 +32,7 @@
 #include <pwd.h>
 #ifdef HAVE_SHADOW_H
 #include <shadow.h>
-#endif
+#endif // HAVE_SHADOW_H
 #include <unistd.h>
 #include <errno.h>
 #include <sys/types.h>
@@ -51,6 +51,25 @@
 #include "user.h"
 #include "accounts-user-generated.h"
 
+#ifndef HAVE_FGETSPENT_R
+static int fgetspent_r(FILE *fp, struct spwd *spbuf, char *buf, size_t buflen, struct spwd **spbufp) {
+       struct spwd *shadow_entry = fgetspent(fp);
+       if(!shadow_entry)
+               return -1;
+       size_t namplen = strlen(shadow_entry->sp_namp);
+       size_t pwdplen = strlen(shadow_entry->sp_pwdp);
+
+       if(namplen + pwdplen + 2 > buflen)
+               return -1;
+
+       *spbufp = memcpy(spbuf, shadow_entry, sizeof(struct spwd));
+       spbuf->sp_namp = strncpy(buf, shadow_entry->sp_namp, namplen + 1);
+       spbuf->sp_pwdp = strncpy(buf + namplen + 1, shadow_entry->sp_pwdp, pwdplen + 1);
+
+       return 0;
+}
+#endif // HAVE_FGETSPENT_R
+
 #define PATH_PASSWD "passwd"
 #define PATH_SHADOW "shadow"
 #define PATH_GROUP "/etc/group"
only in patch2:
unchanged:
--- a/meson.build
+++ b/meson.build
@@ -71,6 +71,7 @@ check_functions = [
   'getusershell',
   'setutxdb',
   'fgetpwent',
+  'fgetspent_r'
 ]
 
 foreach func: check_functions