Restore -mtpcs-frame flag and behavior

[StanHash]

This restores the -m(no-)tpcs-frame and -m(no-)tpcs-leaf-frame flags and their associated behaviors, which were presumably removed from agbcc early on.

When enabled, these have the effect of producing extended function prologue and epilogues like this:

sub     sp, sp, #16     @ Create stack backtrace structure
push    {..., lr}
add     r3, sp, #20
str     r3, [sp, #8]
mov     r3, pc
str     r3, [sp, #16]
mov     r3, fp
str     r3, [sp, #4]
mov     r3, lr
str     r3, [sp, #12]
add     r3, sp, #16
mov     fp, r3          @ Backtrace structure created
@ ...
pop     {...}
pop     {r0, r1, r2}
mov     fp, r1
mov     sp, r2
bx      r0

This is known to be required to match exactly main.c in fe6, fe7 and related projects.