[gdb/testsuite] Compile gdb.dwarf2/dw2-error.exp quietly

When running test-case gdb.dwarf2/dw2-error.exp with target board
cc-with-gdb-index, we get:
...
Running src/gdb/testsuite/gdb.dwarf2/dw2-error.exp ...
gdb compile failed, Dwarf Error: wrong version in compilation unit header \
  (is 153, should be 2, 3, 4 or 5) [in module \
  build/gdb/testsuite/outputs/gdb.dwarf2/dw2-error/.tmp/dw2-error]
...
and similar for target board cc-with-debug-names.

Be less verbose by adding "quiet" to the compile flags.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2020-04-24  Tom de Vries  <tdevries@suse.de>

	* gdb.dwarf2/dw2-error.exp: Add quiet to compile flags.

1 files changed, 1 insertions, 1 deletions

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-error.exp b/gdb/testsuite/gdb.dwarf2/dw2-error.exp
index bd2802f2..5583e36 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-error.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-error.exp
@@ -29,7 +29,7 @@ if { ![istarget "x86_64-*-*"] || ![is_lp64_target] } {
 
 # We can't use prepare_for_testing here because we need to check the
 # 'file' command's output.
-if {[build_executable $testfile.exp $testfile $srcfile {nodebug}]} {
+if {[build_executable $testfile.exp $testfile $srcfile {nodebug quiet}]} {
     return -1
 }