[gdb/testsuite] Make gdb.mi/mi-sym-info.exp more robust against timeouts

Once in a while, I run into this timeout:
...
FAIL: gdb.mi/mi-sym-info.exp: List all variables from debug information \
  only (timeout)
...

I can make the timeout reproducible by setting timeout to 8s (instead of the
default 10s) for the duration of that test.

Make the test-case more stable by fixing all timeouts caused by setting
timeout to 5, either by adding with_timeout_factor, or increasing its factor.

Tested on x86_64-linux.  Also tested in parallel with stress -c 5, to simulate
a busy system in another way.

gdb/testsuite/ChangeLog:

2021-04-30  Tom de Vries  <tdevries@suse.de>

	* gdb.mi/mi-sym-info.exp: Add with_timeout_factor, and increase
	existing timeout factors.

2 files changed, 42 insertions, 33 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 10c7d76..8e021d2 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2021-04-30  Tom de Vries  <tdevries@suse.de>
 
+	* gdb.mi/mi-sym-info.exp: Add with_timeout_factor, and increase
+	existing timeout factors.
+
+2021-04-30  Tom de Vries  <tdevries@suse.de>
+
 	* gdb.mi/mi-sym-info.exp: Remove duplicate test.
 
 2021-04-29  Tom de Vries  <tdevries@suse.de>
diff --git a/gdb/testsuite/gdb.mi/mi-sym-info.exp b/gdb/testsuite/gdb.mi/mi-sym-info.exp
index f7f574a..18f8518 100644
--- a/gdb/testsuite/gdb.mi/mi-sym-info.exp
+++ b/gdb/testsuite/gdb.mi/mi-sym-info.exp
@@ -55,42 +55,46 @@ set type_syms \
 
 # Fetch all functions, variables and types without any non-debug
 # symbols.
-set testname "List all functions from debug information only"
-set cmd "111-symbol-info-functions"
-set state 0
-gdb_test_multiple $cmd $testname -prompt "${mi_gdb_prompt}$" {
-    -re "111\\^done,symbols=\{debug=\\\[${symtab_re}" {
-	if { $state == 0 } { incr state }
-	exp_continue
-    }
-    -re ",${symtab_re}" {
-	exp_continue
-    }
-    -re "\\\]\}\r\n${mi_gdb_prompt}$" {
-	if { $state == 1 } {
-	    pass $gdb_test_name
-	} else {
-	    fail $gdb_test_name
+with_timeout_factor 2 {
+    set testname "List all functions from debug information only"
+    set cmd "111-symbol-info-functions"
+    set state 0
+    gdb_test_multiple $cmd $testname -prompt "${mi_gdb_prompt}$" {
+	-re "111\\^done,symbols=\{debug=\\\[${symtab_re}" {
+	    if { $state == 0 } { incr state }
+	    exp_continue
+	}
+	-re ",${symtab_re}" {
+	    exp_continue
+	}
+	-re "\\\]\}\r\n${mi_gdb_prompt}$" {
+	    if { $state == 1 } {
+		pass $gdb_test_name
+	    } else {
+		fail $gdb_test_name
+	    }
 	}
     }
 }
 
-set testname "List all variables from debug information only"
-set cmd "112-symbol-info-variables"
-set state 0
-gdb_test_multiple $cmd $testname -prompt "${mi_gdb_prompt}$" {
-    -re "112\\^done,symbols=\{debug=\\\[${symtab_re}" {
-	if { $state == 0 } { incr state }
-	exp_continue
-    }
-    -re ",${symtab_re}" {
-	exp_continue
-    }
-    -re "\\\]\}\r\n${mi_gdb_prompt}$" {
-	if { $state == 1 } {
-	    pass $gdb_test_name
-	} else {
-	    fail $gdb_test_name
+with_timeout_factor 2 {
+    set testname "List all variables from debug information only"
+    set cmd "112-symbol-info-variables"
+    set state 0
+    gdb_test_multiple $cmd $testname -prompt "${mi_gdb_prompt}$" {
+	-re "112\\^done,symbols=\{debug=\\\[${symtab_re}" {
+	    if { $state == 0 } { incr state }
+	    exp_continue
+	}
+	-re ",${symtab_re}" {
+	    exp_continue
+	}
+	-re "\\\]\}\r\n${mi_gdb_prompt}$" {
+	    if { $state == 1 } {
+		pass $gdb_test_name
+	    } else {
+		fail $gdb_test_name
+	    }
 	}
     }
 }
@@ -150,7 +154,7 @@ gdb_test_multiple $cmd ${testname} -prompt "${mi_gdb_prompt}$" {
     }
 }
 
-with_timeout_factor 2 {
+with_timeout_factor 4 {
     set testname "List all variables"
     set cmd "115-symbol-info-variables --include-nondebug"
     set state 0