tests: Fix typo in unit test code
This project wasn't actually configured, so it was never noticed.
@@ -3,6 +3,6 @@ project('trivial test',
meson_version : '>=0.27.0')
executable('trivialc', 'trivial.c')
-executable('trivialcpp', 'trivial.cpp')
+executable('trivialcpp', 'trivial.cc')
executable('trivialobjc', 'trivial.m')
executable('trivialobjcpp', 'trivial.mm')
