[scan-build] fix warning emitted on LLVM X86 code base

[apelete]

Summary

Fix logic error warnings of the type "called C++ object pointer is
null" emitted by Clang Static Analyzer on the following file:

• lib/Target/X86/AsmParser/X86AsmParser.cpp.

Signed-off-by: Apelete Seketeli <[e-mail]>

lib/Target/X86/AsmParser/X86AsmParser.cpp

bool X86AsmParser::parseDirectiveEven(SMLoc L) {
   if (getLexer().isNot(AsmToken::EndOfStatement)) {
     TokError("unexpected token in directive");
     return false;  
   }
   if (!Section) {
     getStreamer().InitSections(false);
     Section = getStreamer().getCurrentSection().first;
   }
+  assert(Section && "must have section to emit alignment");
   if (Section->UseCodeAlign())
     getStreamer().EmitCodeAlignment(2, 0);
   else
     getStreamer().EmitValueToAlignment(2, 0, 1, 0);
   return false;
 }
 /// ParseDirectiveWord
 ///  ::= .word [ expression (, expression)* ]