jscript: Change prototype of jsstr_alloc_buf and fix some error handling issues.

[Jacek Caban]

Hi Sebastian,

The patch looks mostly good, but I get a compiler warning (a false one,
but still):

In file included from jsval.h:22:0,
                 from jscript.h:377,
                 from array.c:25:
array.c: In function ‘array_join’:
jsstr.h:109:7: warning: ‘ret’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
     if(!--str->ref)
       ^
array.c:243:25: note: ‘ret’ was declared here
     jsstr_t **str_tab, *ret;
                         ^

Thanks,
Jacek