[gdb/testsuite] Fix gdb.base/sect-cmd.exp

With a testsuite setup modified to make expect wait a little bit longer for
gdb output (see PR27957), I reliably run into:
...
(gdb) FAIL: gdb.base/sect-cmd.exp: set section .text to original \
  address (timeout)
...

The problem is a too greedy regexp:
...
       -re ".*$address1 \- $address2 is $section_name.*" {
...
which ends up consuming the gdb prompt with the terminating ".*".

Fix this by limiting the regexp to a single line.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2021-06-08  Tom de Vries  <tdevries@suse.de>

	* gdb.base/sect-cmd.exp: Fix saw_section_address_line regexp.

gdb/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2021-06-08  Tom de Vries  <tdevries@suse.de>
+
+	* gdb.base/sect-cmd.exp: Fix saw_section_address_line regexp.
+
 2021-06-07  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* gdb.base/continue-all-already-running.exp: Call fail if can't

gdb/testsuite/gdb.base/sect-cmd.exp

@@ -58,7 +58,7 @@ if { $address1 == "" || $address2 == "" || $section_name == "" } {
 set saw_section_address_line false
 gdb_test_multiple "section $section_name $address1" \
     "set section $section_name to original address" {
-	-re ".*$address1 \- $address2 is $section_name.*" {
+	-re ".*$address1 \- $address2 is $section_name in \[^\r\n\]*" {
 	    set saw_section_address_line true
 	    exp_continue
 	}