curl_easy_reset() may be used by an application to reset the options on
a curl handle. If an app has the CURL_IMPERSONATE env var defined, then
the impersonation options are automatically set in curl_easy_init() but
will be cleared in a call to curl_easy_reset(). The desired behavior is
for the impersonation options to be retained (as they are "transparent"
to the user), which this commit takes care of.
Note that this only has an effect when libcurl-impersonate is loaded and
the CURL_IMPERSONATE env var is set. Otherwise the regular behavior of
resetting all the handle options is retained.
Test that the unique TLS signature of curl-impersonate is preserved
after a call to curl_easy_reset() when libcurl-impersonate is loaded.
For this purpose change the 'minicurl' testing util to support multiple
URLs and launch it with 2 different URLs when testing the TLS signature.
Add tests to verify that the HTTP headers and HTTP/2 pseudo-headers
generated by curl-impersonate match the expected ones from the browser.
The test uses a local nghttpd HTTP/2 server instance with a self-signed
certificate.
Test that libcurl-impersonate produces the desired TLS signature when
the CURL_IMPERSONATE env var is set. A small C program called "minicurl"
is linked to libcurl, and libcurl-impersonate is loaded at runtime with
LD_PRELOAD.
