The issue is specific to SLES15.
Arguably this should be reported to them as it seems to me they meddled
with the oniguruma source code.
The definition in oniguruma.h on that platform looks like this (same as upstream):
```c
ONIG_EXTERN
int onig_error_code_to_str PV_((OnigUChar* s, int err_code, ...));
```
Where `PV_` is defined as (differs):
```c
#ifndef PV_
#ifdef HAVE_STDARG_PROTOTYPES
# define PV_(args) args
#else
# define PV_(args) ()
#endif
#endif
```
So that means that `HAVE_STDARG_PROTOTYPES` is unset.
This can be set if we define `HAVE_STDARG_H`,
which we can do because PHP requires at least C99 in which the header
is always available.
We could also use an autoconf check, but this isn't really necessary as
it will always succeed.
to link to the external oniguruma library.
- Prevent libmbfl files from being installed when --with-libmbfl is specified.
- Fixed mb_ereg_replace() to work with unicode strings.
