Fix arm32 local variable references

Fix arm32 local variable references

Arm32 has different addressing mode offset ranges for floating-point
and integer instructions. In addition, the ranges aren't too large.
So in functions with a frame pointer, we try to access some variables
using the frame pointer and some with the stack pointer, to expand the
total number of variables we can access without allocating a "reserved
register" just used for constructing large offsets.

This calculation was incorrect for struct variables that contained floats,
as float fields require calculating using the floating point range, but we
were calculating using the variable type (struct), instead of the instruction
type (floating-point). In addition, we were not correctly calculating the
frame pointer range using the actual variable offset plus "within variable"
offset (struct member offset).

Added a test that covers some of these cases.

Fixes #19537