Save 64 bytes from most Linux/amd64 interpreter frames. (mono/mono#15926)

Save 64 bytes from most Linux/amd64 interpreter frames. (mono/mono#15926)

 Probably same on all 64bit architectures. half on 32bit.

before:
```
0000000000003ce0 <interp_exec_method_full>:
    3ce0:	55                   	push   %rbp
    3ce1:	48 89 e5             	mov    %rsp,%rbp
    3ce4:	41 57                	push   %r15
    3ce6:	41 56                	push   %r14
    3ce8:	41 55                	push   %r13
    3cea:	41 54                	push   %r12
    3cec:	49 89 f4             	mov    %rsi,%r12
    3cef:	53                   	push   %rbx
    3cf0:	48 89 fb             	mov    %rdi,%rbx
    3cf3:	48 81 ec 78 01 00 00 	sub    $0x178,%rsp
```

after:
```
0000000000003ce0 <interp_exec_method_full>:
    3ce0:	55                   	push   %rbp
    3ce1:	48 89 e5             	mov    %rsp,%rbp
    3ce4:	41 57                	push   %r15
    3ce6:	41 56                	push   %r14
    3ce8:	41 55                	push   %r13
    3cea:	41 54                	push   %r12
    3cec:	49 89 f4             	mov    %rsi,%r12
    3cef:	53                   	push   %rbx
    3cf0:	48 89 fb             	mov    %rdi,%rbx
    3cf3:	48 81 ec 38 01 00 00 	sub    $0x138,%rsp
```

It was 0x158 recently.

Some frames will be larger, i.e. dynamic + pinvoke.

Classic technique:
 pointer instead of struct
 initialized to null
 alloca it when needed and not null

A more detailed analysis might enable better, such as making
the parameter optional, and/or having the callee default it to its
local storage.

Commit migrated from https://github.com/mono/mono/commit/e0335d357056f9017f7c170ed41f5cb7e3e32399