Disabling them breaks build on archs using GCC. The problem is at line 156 of
bits/basic_ios.h:
if (this->exceptions() & __state)
__throw_exception_again;
With exceptions disabled __throw_exception_again is defined as
#define __throw_exception_again
at line 45 of exception_defines.h and the code results in an empty loop body,
which fails because of -Werror.
Approved by: cognet
2d2187338e