[lldb][Breakpoint] Allow whitespace in breakpoint address expression

Setting a breakpoint on `<symbol> + <offset>` used to work until
`2c76e88e9eb284d17cf409851fb01f1d583bb22a`, where this regex was
reworked. Now we only accept `<symbol>+ <offset>`.

This patch fixes the regression by adding yet another `[[:space:]]*`
component to the regex.

One could probably simplify the regex (or even replace the regex by just
calling the relevent `consumeXXX` APIs on `llvm::StringRef`). Though I
left that for the future.

rdar://130780342

Author: Michael137

lldb/source/Interpreter/OptionArgParser.cpp

@@ -262,8 +262,10 @@ OptionArgParser::DoToAddress(const ExecutionContext *exe_ctx, llvm::StringRef s,
   // 3: The symbol/reg name if there is an offset
   // 4: +/-
   // 5: The offset value.
+  // clang-format off
   static RegularExpression g_symbol_plus_offset_regex(
-      "^(\\$[^ +-]+)|(([^ +-]+)([-\\+])[[:space:]]*(0x[0-9A-Fa-f]+|[0-9]+)[[:space:]]*)$");
+      "^(\\$[^ +-]+)|(([^ +-]+)[[:space:]]*([-\\+])[[:space:]]*(0x[0-9A-Fa-f]+|[0-9]+)[[:space:]]*)$");
+  // clang-format on
 
   llvm::SmallVector<llvm::StringRef, 4> matches;
   if (g_symbol_plus_offset_regex.Execute(sref, &matches)) {