[gdb/testsuite] Skip dap tests for tcl 8.5

When running the dap tests on a system with tcl 8.5, we run into:
...
ERROR: tcl error sourcing gdb/testsuite/gdb.dap/memory.exp.
ERROR: bad class "entier": must be alnum, alpha, ascii, control, boolean, \
  digit, double, false, graph, integer, list, lower, print, punct, space, \
  true, upper, wideinteger, wordchar, or xdigit
    while executing
"string is entier $num"
    (procedure "num" line 16)
    invoked from within
...

Fix this by:
- requiring tcl 8.6 in allow_dap_tests, and
- adding the missing require allow_dap_tests in gdb.dap/memory.exp.

Tested on x86_64-linux.

2 files changed, 7 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.dap/memory.exp b/gdb/testsuite/gdb.dap/memory.exp
index fec552c4..ab0516d 100644
--- a/gdb/testsuite/gdb.dap/memory.exp
+++ b/gdb/testsuite/gdb.dap/memory.exp
@@ -15,6 +15,8 @@
 
 # Test DAP read/write memory.
 
+require allow_dap_tests
+
 load_lib dap-support.exp
 
 standard_testfile
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 9ea0334..b59b435 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -2515,6 +2515,11 @@ gdb_caching_proc allow_dap_tests {} {
 	return 0
     }
 
+    # ton.tcl uses "string is entier", supported starting tcl 8.6.
+    if { ![tcl_version_at_least 8 6] } {
+	return 0
+    }
+
     # With set auto-connect-native-target off, we run into:
     # +++ run
     # Traceback (most recent call last):