[NFC] Correctly assert the indents for printEnumValHelpStr.

[fodinabor]

Summary

Only verify that there's no negative indent.
Noted by @chapuni in https://reviews.llvm.org/D93494.

[chapuni]

Okay, it's fair.
(May I wait for 3rd opinion?)

[chapuni]

Please remind to feed it into release/12.x, thanks!

[fodinabor]

Landed and added to release blockers for 12.0.1

llvm/lib/Support/CommandLine.cpp

while (!Split.second.empty()) {
     Split = Split.second.split('\n');
     outs().indent(Indent) << Split.first << "\n";
   }
 }
 
 void Option::printEnumValHelpStr(StringRef HelpStr, size_t BaseIndent,
                                  size_t FirstLineIndentedBy) {
   const StringRef ValHelpPrefix = "  ";
-  assert(BaseIndent >= FirstLineIndentedBy + ValHelpPrefix.size());
+  assert(BaseIndent >= FirstLineIndentedBy);
   std::pair<StringRef, StringRef> Split = HelpStr.split('\n');
   outs().indent(BaseIndent - FirstLineIndentedBy)
       << ArgHelpPrefix << ValHelpPrefix << Split.first << "\n";
   while (!Split.second.empty()) {
     Split = Split.second.split('\n');
     outs().indent(BaseIndent + ValHelpPrefix.size()) << Split.first << "\n";
   }
 }