Force project includes before system includes (fixes #763)

From time to time, someone has a problem because their build is
grabbing an old version of qpdf header files that are installed
somewhere on their system. I am hoping this will put an end to that.

CMakeLists.txt

@@ -111,6 +111,7 @@ if(NOT (BUILD_STATIC_LIBS OR BUILD_SHARED_LIBS))
     FATAL_ERROR "At least one of static or shared libraries must be built")
 endif()
 
+set(CMAKE_INCLUDE_DIRECTORIES_PROJECT_BEFORE ON)
 add_compile_definitions($<$<COMPILE_LANGUAGE:CXX>:POINTERHOLDER_TRANSITION=4>)
 
 if(ENABLE_QTC)

ChangeLog

@@ -1,3 +1,9 @@
+2022-09-14  Jay Berkenbilt  <ejb@ql.org>
+
+        * Set CMAKE_INCLUDE_DIRECTORIES_PROJECT_BEFORE ON in cmake to
+        (hopefully) solve the problem of older installed qpdf headers
+        interfering with building qpdf from source. Fixes #763.
+
 2022-09-12  Jay Berkenbilt  <ejb@ql.org>
 
         * Add some missing DLL exports that only affect the Windows build.

manual/release-notes.rst

@@ -17,6 +17,10 @@ For a detailed list of changes, please see the file
     - Some symbols were not properly exported for the Windows DLL
       build.
 
+    - Force project-specific header files to precede all others in the
+      build so that a previous qpdf installation won't break building
+      qpdf from source.
+
   - Packaging note omitted from 11.0.0 release notes:
 
     - On GitHub, the release tags are now `vX.Y.Z` instead of