patch 8.1.0312: wrong type for flags used in signal handlers

Problem:    Wrong type for flags used in signal handlers.
Solution:   Use sig_atomic_t. (Dominique Pelle, closes #3356)
diff --git a/src/globals.h b/src/globals.h
index 09820cf..fa5b493 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -518,7 +518,7 @@
  *
  * volatile because it is used in signal handler sig_sysmouse().
  */
-EXTERN volatile int hold_gui_events INIT(= 0);
+EXTERN volatile sig_atomic_t hold_gui_events INIT(= 0);
 
 /*
  * When resizing the shell is postponed, remember the new size, and call
@@ -655,7 +655,7 @@
 				/* TRUE when in or after free_all_mem() */
 #endif
 /* volatile because it is used in signal handler deathtrap(). */
-EXTERN volatile int full_screen INIT(= FALSE);
+EXTERN volatile sig_atomic_t full_screen INIT(= FALSE);
 				/* TRUE when doing full-screen output
 				 * otherwise only writing some messages */
 
@@ -800,11 +800,11 @@
 EXTERN JMP_BUF lc_jump_env;	/* argument to SETJMP() */
 # ifdef SIGHASARG
 /* volatile because it is used in signal handlers. */
-EXTERN volatile int lc_signal;	/* caught signal number, 0 when no was signal
+EXTERN volatile sig_atomic_t lc_signal;	/* caught signal number, 0 when no was signal
 				   caught; used for mch_libcall() */
 # endif
 /* volatile because it is used in signal handler deathtrap(). */
-EXTERN volatile int lc_active INIT(= FALSE); /* TRUE when lc_jump_env is valid. */
+EXTERN volatile sig_atomic_t lc_active INIT(= FALSE); /* TRUE when lc_jump_env is valid. */
 #endif
 
 #if defined(FEAT_MBYTE) || defined(FEAT_POSTSCRIPT)
@@ -1037,7 +1037,7 @@
 EXTERN int	read_cmd_fd INIT(= 0);	    /* fd to read commands from */
 
 /* volatile because it is used in signal handler catch_sigint(). */
-EXTERN volatile int got_int INIT(= FALSE);    /* set to TRUE when interrupt
+EXTERN volatile sig_atomic_t got_int INIT(= FALSE); /* set to TRUE when interrupt
 						signal occurred */
 #ifdef USE_TERM_CONSOLE
 EXTERN int	term_console INIT(= FALSE); /* set to TRUE when console used */