Fix a couple of corner cases in NameMatches

Summary:
I originally set out to move the NameMatches closer to the relevant
function and add some unit tests. However, in the process I've found a
couple of bugs in the implementation:
- the early exits where not always correct:
  - (test==pattern) does not mean the match will always suceed because
    of regular expressions
  - pattern.empty() does not mean the match will fail because the "" is
    a valid prefix of any string

So I cleaned up those and added some tests. The only tricky part here
was that regcomp() implementation on darwin did not recognise the empty
string as a regular expression and returned an REG_EMPTY error instead.
The simples fix here seemed to be to replace the empty expression with
an equivalent non-empty one.

Reviewers: clayborg, zturner

Subscribers: mgorny, lldb-commits

Differential Revision: https://reviews.llvm.org/D30094

llvm-svn: 295651
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index de11a36..a8805d6 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -1962,29 +1962,29 @@
       bool has_name_match = false;
       if (name && name[0]) {
         has_name_match = true;
-        NameMatchType name_match_type = match_info.GetNameMatchType();
+        NameMatch name_match_type = match_info.GetNameMatchType();
         switch (name_match_type) {
-        case eNameMatchIgnore:
+        case NameMatch::Ignore:
           has_name_match = false;
           break;
 
-        case eNameMatchEquals:
+        case NameMatch::Equals:
           packet.PutCString("name_match:equals;");
           break;
 
-        case eNameMatchContains:
+        case NameMatch::Contains:
           packet.PutCString("name_match:contains;");
           break;
 
-        case eNameMatchStartsWith:
+        case NameMatch::StartsWith:
           packet.PutCString("name_match:starts_with;");
           break;
 
-        case eNameMatchEndsWith:
+        case NameMatch::EndsWith:
           packet.PutCString("name_match:ends_with;");
           break;
 
-        case eNameMatchRegularExpression:
+        case NameMatch::RegularExpression:
           packet.PutCString("name_match:regex;");
           break;
         }