Align CMake and pkgconf include paths

Author: kmilos

src/core/CMakeLists.txt

@@ -137,7 +137,7 @@ endif()
 ## include library version/name
 set_target_properties(openjph PROPERTIES POSITION_INDEPENDENT_CODE ON)
 target_compile_definitions(openjph PUBLIC _FILE_OFFSET_BITS=64)
-target_include_directories(openjph PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/common> $<INSTALL_INTERFACE:include/openjph>)
+target_include_directories(openjph PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/common> $<INSTALL_INTERFACE:include>)
 
 if (MSVC)
   set(OJPH_LIB_NAME_STRING "openjph.${OPENJPH_VERSION_MAJOR}.${OPENJPH_VERSION_MINOR}")