BR3066383: Restore backward compatibility with token pasting

BR3066383: Restore backward compatibility with token pasting

It seems to be a bit long story for the reason if this bug. But
lets be verbose and describe all byte-to-byte. And it is all about
preprocessor code, in particular paste_tokens and expand_mmac_params.

Initially the problem (not the same but similar) was noticed and
fixed in commit ec88c1be. The problem reveals itself with code snippets
like

 | %macro m 1
 |  %push
 |      %define %$arg %1
 | %%top_%$arg:
 |      resb ($ - %%top_%$arg)
 |  %pop
 | %endmacro

So with commits ec88c1be, 51fd86e0, 1f6741fc, 985d880c we did expand
local single macro before processing tokens pasting unconditionally.

But then it being found that such approach breaks %assign directive.
The snippets like below didn't work

 | %macro m 1
 |  %push
 |      %assign %$arg %1
 |      %assign %$arg %1+%$arg
 |  %pop
 | %endmacro

So all these commits were reverted and we just stop pasting tokens
in paste_tokens() after TOK_PREPROC_ID (commit 20a94ad7). Unfortunately
this breaks %assign with compound preproc id

 | %macro m3 1
 |    %push
 |        %assign %$_uses 0
 |        %rep 4
 |            %assign %$_ur%$_uses %$_uses
 |            mov ecx, %$_ur%$_uses
 |            %assign %$_uses %$_uses+1
 |        %endrep
 |    %pop
 | %endmacro

To fix this bug we have to combine two approaches at once,
we should continue pasting after TOK_PREPROC_ID and expand
sequential TOK_PREPROC_IDs except first one.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>