Use Nginx core function in ngx_http_lua_rebase_path

[Someguynamedpie]

Using the Nginx core function for pathing. Had to cast away volatility but it shouldn't be an issue.

I release my changes into the public domain.

[agentzh]

@Someguynamedpie Thanks for your patch. But will you fix the coding style of your changes to be strictly aligned up with the rest of the code base? Many thanks!

[agentzh]

ngx_palloc may return NULL and we should handle this case.

[agentzh]

@Someguynamedpie It's recommended to always run the ngx-releng tool to check your code:

https://github.com/openresty/nginx-devel-utils/blob/master/ngx-releng

The errors found by ngx-releng against your branch on my side are as follows:

src/ngx_http_lua_util.c
376:
379:
382:
385:
388:
391:
src/ngx_http_lua_util.c
389:    if(ngx_get_full_name(pool, (ngx_str_t*)&ngx_cycle->prefix, &nsrc))
not check NULL: src/ngx_http_lua_util.c: line 383:     nsrc.data = ngx_palloc(pool, len+1);
    if (!nsrc.data)

src/ngx_http_lua_util.c:
variable name should align with the previous line
375:     u_char *optr;
found unnecessary tail space
376:
found unnecessary tail space
379:
need space before +
381:     nsrc.data = ngx_palloc(pool, len+1);
need space after +
381:     nsrc.data = ngx_palloc(pool, len+1);
found unnecessary tail space
382:
found unnecessary tail space
385:
found unnecessary tail space
388:
need space before *
389:     if(ngx_get_full_name(pool, (ngx_str_t*)&ngx_cycle->prefix, &nsrc))
found unnecessary tail space
391:

[Someguynamedpie]

Apologies, wasn't aware there were tools to encourage following the coding style. Most of the style issues are actually because I made the mistake of copying it from the terminal haha. I'll work on cleaning it up tonight.

[agentzh]

@Someguynamedpie Thanks for your patience and help!

[agentzh]

@Someguynamedpie Well, I've just rewrote your patch and committed it to git master. Please let me know if it works for you on Win32.