getopt() returns int

See getopt(3): returns int, so store it in an int variable.
I went through all occurrences, project-wide. All return values of
getopt() should be stored in ints now.

openair1/SIMULATION/NR_PHY/prachsim.c

@@ -117,7 +117,6 @@ int NB_UE_INST = 1;
 configmodule_interface_t *uniqCfg = NULL;
 int main(int argc, char **argv){
 
-  char c;
   get_softmodem_params()->sl_mode = 0;
   double sigma2, sigma2_dB = 0, SNR, snr0 = -2.0, snr1 = 0.0, ue_speed0 = 0.0, ue_speed1 = 0.0;
   double **s_re, **s_im, **r_re, **r_im, iqim = 0.0, delay_avg = 0, ue_speed = 0, fs=-1, bw;
@@ -155,6 +154,7 @@ int main(int argc, char **argv){
 
   randominit(0);
 
+  int c;
   while ((c = getopt (argc, argv, "--:O:hHaA:Cc:l:r:p:g:m:n:s:S:t:x:y:v:V:z:N:F:d:Z:L:R:E")) != -1) {
 
     /* ignore long options starting with '--', option '-O' and their arguments that are handled by configmodule */