curl_getenv - return value for environment name
char *curl_getenv(const char *name);
curl_getenv() is a portable wrapper for the getenv() function, meant to
emulate its behaviour and provide an identical interface for all
operating systems libcurl builds on (including win32).
This function will be removed from the public libcurl API in a near
future. It will instead be made "available" by source code access only,
and then as curlx_getenv().
If successful, curl_getenv() returns a pointer to the value of the
specified environment. The memory it refers to is malloc()ed so the
application must free() this when the data is no longer needed. When
curl_getenv(3) fails to find the specified name, it returns a null
Under unix operating systems, there isn’t any point in returning an
allocated memory, although other systems won’t work properly if this
isn’t done. The unix implementation thus has to suffer slightly from
the drawbacks of other systems.