lupdate cannot correctly parse ' (spliter) in numbers

C++ standard allows using ' as a spliter when writing hex numbers for better readability, such as:

unsigned long long x = 0x00000000'00000000;

This, however, does not work well with Qt Linguist tools lupdate. Not only it will warn "Unterminated C++ character", but also can it affect later tr() parsing IN CERTAIN CASES.

Attached is a minimal test to reproduce this issue.

Steps to reproduce:

• Unzip it
• Run

  lupdate QtBugTest.pro -ts en.ts

• EXPECTED:

  Updating 'en.ts'...
      Found 1 source text(s) (1 new and 0 already existing)

• ACTUAL:

  xxx/mainwindow.cpp:6: Unterminated C++ character
  xxx/mainwindow.cpp:7: Unterminated C++ character
  xxx/mainwindow.cpp:8: Unterminated C++ character
  xxx/mainwindow.cpp:11: Excess closing brace in C++ code (or abuse of the C++ preprocessor)
  xxx/mainwindow.cpp:16: tr() cannot be called without context
  xxx/mainwindow.cpp:7: Unbalanced opening parenthesis in C++ code (or abuse of the C++ preprocessor)
  Updating 'en.ts'...
      Found 0 source text(s) (0 new and 0 already existing)

I had the issue on my Qt 5.10.0 MSVC AND Qt 5.11.1 MinGW.

Thank you!