[Bug bootstrap/90132] make bootstrap fails with -O3 (gcc9 snapshot 20190414)

[jayrusman at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90132

--- Comment #5 from Jason Mancini <jayrusman at hotmail dot com> ---
But bootstrap-O3 is a documented target, which is equivalent to BOOT_CFLAGS='-g
-O3', per https://gcc.gnu.org/install/build.html