add support for a password callback

In order to be able to load password-protected key files a password
callback was added.

This also adds support for PKCS#12 containers instead of certificate+key.

Signed-off-by: Steffen Jaeckel <jaeckel-floss@eyet-services.de>

Makefile.am

@@ -114,7 +114,9 @@ EXTRA_DIST = \
 	jni/Application.mk \
 	src/tls_schannel.c \
 	tests/cert.pem \
+	tests/cert.pfx \
 	tests/key.pem \
+	tests/key_encrypted.pem \
 	tests/res_query_dump.c
 
 ## Examples