[committed][gdb/testsuite] Fix gdb.dwarf2/dw2-error.exp with -readnow

[Tom de Vries <tdevries@suse.de>]

Hi,

With test-case gdb.dwarf2/dw2-error.exp and target board readnow, we get:
...
FAIL: gdb.dwarf2/dw2-error.exp: break -q main
...

In the normal case, after running into the dwarf error, the minimal symbols
are still available, but with -readnow this is not the case.

Mark the FAIL as KFAIL.

Tested on x86_64-linux.

Committed to trunk.

Thanks,
- Tom

[gdb/testsuite] Fix gdb.dwarf2/dw2-error.exp with -readnow

gdb/testsuite/ChangeLog:

2020-10-28  Tom de Vries  <tdevries@suse.de>

	* gdb.dwarf2/dw2-error.exp: Mark failure break in main as known with
	-readnow.

---
 gdb/testsuite/gdb.dwarf2/dw2-error.exp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-error.exp b/gdb/testsuite/gdb.dwarf2/dw2-error.exp
index e698752212..345cc11709 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-error.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-error.exp
@@ -44,5 +44,14 @@ gdb_test "file $binfile" \
     {Reading symbols.*Dwarf Error: wrong version in compilation unit header \(is 153, should be 2, 3, 4 or 5\).*} \
     "file $testfile"
 
+# We can't use proc readnow, because the PR makes it return 0.
+gdb_test_multiple "maint print objfiles $binfile" "" {
+    -re "^maint print objfiles \[^\r\n\]*\r\n$gdb_prompt $" {
+	setup_kfail "gdb/26797" *-*-*
+    }
+    -re -wrap "" {
+    }
+}
+
 # Now check that we can still break given the minimal symbol.
 gdb_test "break -q main" "Breakpoint $decimal.*"