[PATCH v2] newlib: fix build with <gcc-5 versions

Solution was quick attempt at original i386 problem, I am aware one 
would need to break down for actual 64 or 128 bit returns and could use 
96,160 bit math depending
on what (a) and (b) enter as, but question of why 0 if is to be newlib 
supplied.
Curiousity
Steve
 >On 20 Mar 2022 12:13, I wrote:
 >I'm probably out of my depth, but along the same question:
 >Why 0 return and not ((bool)(((unsigned long long)(a) * (b)) >> 32))
 >or prepend with '!!'?