preproc: Issue warning on unterminated %{ construct
preproc: Issue warning on unterminated %{ construct

As being pointed by "matching braces" topic on
[ http://forum.nasm.us/index.php?topic=905.0 ]
we don't issue warning on missed match for "{"
brace opened.

Strictly speaking we should issue error instead and
force user to fix asm source code but since it's
here for a long time already -- lets be "admissive".

Reported-by: Klod
CC: Frank Kotler <576e266b023e5671b20b0df7a79abc544fa7199a@zytor.com>
Signed-off-by: Cyrill Gorcunov <7a1ea01eee6961eb1e372e3508c2670446d086f4@gmail.com>

projedi/nasm,projedi/nasm,turingstudio/nasm,projedi/nasm,Distrotech/nasm,techkey/nasm,techkey/nasm,techkey/nasm,letolabs/nasm,projedi/nasm,turingstudio/nasm,Distrotech/nasm,turingstudio/nasm,letolabs/nasm,letolabs/nasm,techkey/nasm,projedi/nasm,turingstudio/nasm,techkey/nasm,Distrotech/nasm,Distrotech/nasm