[cfe-dev] Crash with incorrect _Bool->_Bool conversion

[Eli Friedman]

So that I don't lose track, posting this testcase here:

_Bool x; int a() {if (x);}

Essentially, EmitScalarConversion is assuming that since the source
and destination types are the same, no conversion is needed, which is
wrong in this case.  (Although maybe loading a boolean variable should
immediately truncate it to i1; not sure what the right fix is here.)

-Eli