Bug report #1824894 (http://curl.haxx.se/bug/view.cgi?id=1824894) pointed out a problem in curl.h when building C++ apps with MSVC. To fix it, the inclusion of header files in curl.h is moved outside of the C++ extern "C" linkage block. 
diff --git a/RELEASE-NOTES b/RELEASE-NOTES index f24e647..633c6f8 100644 --- a/RELEASE-NOTES +++ b/RELEASE-NOTES 
@@ -17,6 +17,7 @@  o curl-config --features and --protocols show the correct output when built  with NSS, and also when SCP, SFTP and libz are not available  o free problem in the curl tool for users with empty home dir + o curl.h version 7.17.1 problem when building C++ apps with MSVC    This release includes the following known bugs: