Refine the 'watchpoint set' command to now require either the '-v' option (for watching of a variable) or
the '-e' option (for watching of an address) to be present.

Update some existing test cases with the required option and add some more test cases.

Since the '-v' option takes <variable-name> and the '-e' option takes <expr> as the command arg,
the existing infrastructure for generating the option usage can produce confusing help message,
like:

  watchpoint set -e [-w <watch-type>] [-x <byte-size>] <variable-name | expr>
  watchpoint set -v [-w <watch-type>] [-x <byte-size>] <variable-name | expr>

The solution adopted is to provide an extra member field to the struct CommandArgumentData called
(uint32_t)arg_opt_set_association, whose purpose is to link this particular argument data with some
option set(s).  Also modify the signature of CommandObject::GetFormattedCommandArguments() to:

  GetFormattedCommandArguments (Stream &str, uint32_t opt_set_mask = LLDB_OPT_SET_ALL)

it now takes an additional opt_set_mask which can be used to generate a filtered formatted command
args for help message.

Options::GenerateOptionUsage() impl is modified to call the GetFormattedCommandArguments() appropriately.
So that the help message now looks like:

  watchpoint set -e [-w <watch-type>] [-x <byte-size>] <expr>
  watchpoint set -v [-w <watch-type>] [-x <byte-size>] <variable-name>

rdar://problem/10703256


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@150032 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Interpreter/OptionGroupWatchpoint.cpp b/source/Interpreter/OptionGroupWatchpoint.cpp
index 159d00e..4a6afb4 100644
--- a/source/Interpreter/OptionGroupWatchpoint.cpp
+++ b/source/Interpreter/OptionGroupWatchpoint.cpp
@@ -40,8 +40,8 @@
 static OptionDefinition
 g_option_table[] =
 {
-    { LLDB_OPT_SET_1, false, "watch", 'w', required_argument, g_watch_type, 0, eArgTypeWatchType, "Determine how to watch a variable; or, with -x option, its pointee."},
-    { LLDB_OPT_SET_1, false, "xsize", 'x', required_argument, g_watch_size, 0, eArgTypeByteSize, "Number of bytes to use to watch the pointee."}
+    { LLDB_OPT_SET_1, false, "watch", 'w', required_argument, g_watch_type, 0, eArgTypeWatchType, "Specify the type of watching to perform."},
+    { LLDB_OPT_SET_1, false, "xsize", 'x', required_argument, g_watch_size, 0, eArgTypeByteSize, "Number of bytes to use to watch a region."}
 };