Remove some more unused build system code
Give hsc2hs different options in different stages; fixes #7705

Based on patch from Stephen Blackheath.
Use .globl rather than .global on arm; part of #7707

Apparently ios only understands .globl, but Linux appears to understand
both.
Use 'r11' rather than 'fp' on Arm; part of #7707

They're both the same register, and Linux seems happy with both,
but ios only accepts r11.
ios fix from Stephen Blackheath; part of #7707

Apparently ios doesn't understand .type %function.
Add OSiOS, and define and use platformUsesFrameworks; part of #7720