Missing headers in files

[mohd-akram]

Trying to compile this on macOS 10.10 fails due to missing headers:

src/infrastructure/filesystem.cc:36:9: error: use of undeclared identifier 'errno'
    if (errno == ENOENT) {
        ^
src/infrastructure/filesystem.cc:36:18: error: use of undeclared identifier 'ENOENT'
    if (errno == ENOENT) {
                 ^
2 errors generated.
make[2]: *** [CMakeFiles/ampache_browser.dir/src/infrastructure/filesystem.cc.o] Error 1
make[2]: *** Waiting for unfinished jobs....
src/infrastructure/os_paths.cc:33:23: error: use of undeclared identifier 'getenv'
    if ((configHome = getenv("XDG_CONFIG_HOME")) && configHome[0] == PATH_SEP[0]) {
                      ^
src/infrastructure/os_paths.cc:45:22: error: use of undeclared identifier 'getenv'
    if ((cacheHome = getenv("XDG_CACHE_HOME")) && cacheHome[0] == PATH_SEP[0]) {
                     ^
src/infrastructure/os_paths.cc:65:17: error: use of undeclared identifier 'getenv'
    if ((home = getenv("HOME")) && home[0] == PATH_SEP[0]) {

It seems stdlib.h in os_paths.cc (for getenv) and errno.h in filesystem.cc are required.