When the '-mno-x87' command line option is used, it should prevent all generation
of x87 instructions. Currently there are several circumstances under which it does not.
For example: https://godbolt.org/z/qnPaW7dd6
This patch adds "HasX87" predicates to each X87 instructions and when 80-bit
float pointer is supposed to pass or return on the x87 stack, reporting
an error if X87 is not supported.