Add noexcept to custom non-throwing new operators.

Both libc++ and libstdc++ declare non-throwing new operators as
noexcept and overloads must also be noexcept.  This fixes a
-Wmissing-exception-spec warning with clang.

gdb/ChangeLog:

	* common/new-op.c (operator new): Mark 'noexcept'.
	(operator new[]): Likewise.
2 files changed