Fix a build issue due to previous CMake change (#744)

The problem is that the Readline/zlib include paths were being included
before our own include path (wrong import order). This caused a problem
if the zlib include path was /usr/local/include, and that directory
happened to unfortunately contain a pcre2.h file for an (older) version
of PCRE2.

Author: NWilson

CMakeLists.txt

@@ -145,7 +145,7 @@ endif()
 # setting CMAKE_MODULE_PATH on the command line.
 list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
 
-include_directories(${PROJECT_BINARY_DIR}/src ${PROJECT_SOURCE_DIR}/src)
+include_directories(${PROJECT_BINARY_DIR}/interface ${PROJECT_BINARY_DIR}/src ${PROJECT_SOURCE_DIR}/src)
 
 # external packages
 find_package(BZip2)