Reduce false positives with verify-flag-underscore.sh by updating regex

Check to make sure there is not an alphanumeric character immeditely
before or after the 'flag'.  It there is an alphanumeric character then
this is obviously not actually the flag we care about.  For example if
the project declares a flag "valid-name" but the regex finds something
like "invalid_name" we should not match.  Clearly this "invalid_name" is
not actually a wrong usage of the "valid-name" flag.

hack/verify-flags-underscore.py

@@ -96,11 +96,10 @@ def normalize_files(rootdir, files):
     return newfiles
 
 def line_has_bad_flag(line, flagre):
-    m  = flagre.search(line)
-    if not m:
-        return False
-    if "_" in m.group(0):
-        return True
+    results  = flagre.findall(line)
+    for result in results:
+        if "_" in result:
+            return True
     return False
 
 # The list of files might not be the whole repo. If someone only changed a
@@ -155,7 +154,7 @@ def flags_to_re(flags):
     for flag in flags:
         # turn all flag names into regexs which will find both types
         newre = dashRE.sub('[-_]', flag)
-        flagREs.append(newre)
+        flagREs.append("[^\w]" + newre + "[^\w]")
     # turn that list of regex strings into a single large RE
     flagRE = "|".join(flagREs)
     flagRE = re.compile(flagRE)