zlib_base function names must differ from their zlib counterpart

[robert.bielik@…]

If Z_PREFIX has been used to compile zlib, boost::iostreams must adhere to that, but because a few names (inflate/deflate/alloc_func/free_func) are defined in zlib's zconf.h file where Z_PREFIX is used to add a z_ prefix, boost::iostreams zlib.cpp will fail to compile. Proposed name changes: zlib_base::inflate -> zlib_base::zlib_inflate zlib_base::deflate -> zlib_base::zlib_deflate typedef zlib::alloc_func -> zlib::alloc_function typedef zlib::free_func -> zlib::free_function

[Jonathan Turkanis]

(In [45783]) added 'x' prefix to several function and type names, to prevent them from being renamed by the preprocessor when Z_PREFIX is defined (fixes #1870)