remove kdevplatform from #include paths
This fixes the build for me.
"The kdevplatform/ prefix may find system-wide KDevPlatform headers, if they are installed. If not, a compilation error occurs. Even if the headers are installed, they shouldn't be used to compile the plugins. Instead the KDevPlatform headers from the same repository should be included, e.g. #include <project/projectmodel.h>." kdevelop/kdevelop!128 (comment 146245)