CI Tests: fix Regression/bz1563046-getlogin-r-return-early-when-linux-sentinel-value

* add gcc to required packages
* include 'unistd.h'

tests/Regression/bz1563046-getlogin-r-return-early-when-linux-sentinel-value/main.fmf

@@ -16,6 +16,7 @@ recommend:
   - glibc-debuginfo
   - glibc-debuginfo-common
   - gdb
+  - gcc
 duration: 30m
 extra-summary:
   /tools/glibc/Regression/bz1563046-getlogin-r-return-early-when-linux-sentinel-value

tests/Regression/bz1563046-getlogin-r-return-early-when-linux-sentinel-value/tst-getlogin_r.c

@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 #define BUFSIZE 1024
 int main(int argc, char *argv[]) {
 	int r=0,i,attempts=0;