[gdb/testsuite] Remove inferior output in gdb.base/foll-vfork.exp

Test-case gdb.base/foll-vfork.exp has inferior output that is not needed, but
which makes the regexp matching more difficult (see commit 1f28b70def
"[gdb/testsuite] Fix regexp in gdb.base/foll-vfork.exp").

Remove the inferior output, and revert commit 1f28b70def to make the matching
more restrictive.

Tested on x86_64-linux.

gdb/testsuite/gdb.base/foll-vfork-exit.c

@@ -29,12 +29,12 @@ main ()
   pid = vfork (); /* VFORK */
   if (pid == 0)
     {
-      printf ("I'm the child!\n");
+      const char *volatile s = "I'm the child!";
       _exit (0);
     }
   else
     {
-      printf ("I'm the proud parent of child #%d!\n", pid);
+      const char *volatile s = "I'm the proud parent of child";
     }
 
   return 0;

gdb/testsuite/gdb.base/foll-vfork.c

@@ -40,12 +40,11 @@ main (int argc, char ** argv)
     memcpy (prog + len - 10, "vforked-prog", 12);
     prog[len + 2] = 0;
 
-    printf ("I'm the child!\n");
     execlp (prog, prog, (char *) 0);
     perror ("exec failed");
     _exit (1);
   }
   else {
-    printf ("I'm the proud parent of child #%d!\n", pid);
+    const char *volatile s = "I'm the proud parent of child";
   }
 }

gdb/testsuite/gdb.base/foll-vfork.exp

@@ -119,7 +119,7 @@ proc vfork_parent_follow_to_bp {} {
 
    gdb_test_no_output "set follow-fork parent"
 
-   set bp_location [gdb_get_line_number "printf (\"I'm the proud parent of child"]
+   set bp_location [gdb_get_line_number "I'm the proud parent of child"]
    gdb_test "break ${srcfile}:${bp_location}" ".*" "break, vfork to bp"
 
    set test "continue to bp"
@@ -169,7 +169,7 @@ proc vfork_and_exec_child_follow_to_main_bp {} {
 
    gdb_test_no_output "set follow-fork child"
 
-   set linenum [gdb_get_line_number "printf(\"Hello from vforked-prog" ${srcfile2}]
+   set linenum [gdb_get_line_number "Hello from vforked-prog" ${srcfile2}]
 
    set test "continue to bp"
    gdb_test_multiple "continue" $test {
@@ -271,7 +271,7 @@ proc tcatch_vfork_then_child_follow_exec {} {
    continue_to_vfork
 
    set linenum1 [gdb_get_line_number "pid = vfork ();"]
-   set linenum2 [gdb_get_line_number "printf(\"Hello from vforked-prog" ${srcfile2}]
+   set linenum2 [gdb_get_line_number "Hello from vforked-prog" ${srcfile2}]
 
    set test "finish"
    gdb_test_multiple "finish" $test {
@@ -349,7 +349,7 @@ proc vfork_relations_in_info_inferiors { variant } {
    if { $variant == "exec" } {
        global srcfile2
 
-       set linenum [gdb_get_line_number "printf(\"Hello from vforked-prog" ${srcfile2}]
+       set linenum [gdb_get_line_number "Hello from vforked-prog" ${srcfile2}]
        set test "continue to bp"
        gdb_test_multiple "continue" $test {
 	   -re ".*xecuting new program.*Breakpoint.*vforked-prog.c:${linenum}.*$gdb_prompt " {
@@ -367,13 +367,13 @@ proc vfork_relations_in_info_inferiors { variant } {
 
    set test "vfork relation no longer appears in info inferiors"
    gdb_test_multiple "info inferiors" $test {
-       -re "is vfork child of inferior 1.*$gdb_prompt " {
+       -re -wrap "is vfork child of inferior 1.*" {
 	   fail $test
        }
-       -re "is vfork parent of inferior 2.*$gdb_prompt " {
+       -re -wrap "is vfork parent of inferior 2.*" {
 	   fail $test
        }
-       -re "$gdb_prompt " {
+       -re -wrap "" {
 	   pass $test
        }
    }

gdb/testsuite/gdb.base/vforked-prog.c

@@ -19,6 +19,6 @@
 
 int main (void)
 {
-  printf("Hello from vforked-prog...\n");
+  const char *volatile s = "Hello from vforked-prog";
   return 0;
 }