Configure QDLDL include files to build directory

Configuring into the source tree means the configured headers will clash
if you try to build multiple configurations at once, so instead
configure them into the build directory and then use those and install
those to ensure each configuration has the correct header.

CMakeLists.txt

@@ -103,11 +103,11 @@ set(QDLDL_BOOL_TYPE "unsigned char")
 # Generate header file with the global options
 # ---------------------------------------------
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/configure/qdldl_types.h.in
-               ${CMAKE_CURRENT_SOURCE_DIR}/include/qdldl_types.h
+               ${CMAKE_CURRENT_BINARY_DIR}/include/qdldl_types.h
                NEWLINE_STYLE LF)
 
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/configure/qdldl_version.h.in
-               ${CMAKE_CURRENT_SOURCE_DIR}/include/qdldl_version.h
+               ${CMAKE_CURRENT_BINARY_DIR}/include/qdldl_version.h
                NEWLINE_STYLE LF)
 
 
@@ -121,14 +121,16 @@ set(
 set(
 	qdldl_headers
 	include/qdldl.h
-	include/qdldl_types.h
-	include/qdldl_version.h
+	${CMAKE_CURRENT_BINARY_DIR}/include/qdldl_types.h
+	${CMAKE_CURRENT_BINARY_DIR}/include/qdldl_version.h
 	)
 
 # Create object library
 # ----------------------------------------------
 add_library (qdldlobject OBJECT ${qdldl_src} ${qdldl_headers})
-target_include_directories(qdldlobject PRIVATE ${PROJECT_SOURCE_DIR}/include)
+target_include_directories(qdldlobject PRIVATE
+                           ${CMAKE_CURRENT_SOURCE_DIR}/include
+                           ${CMAKE_CURRENT_BINARY_DIR}/include)
 
 
 # Create Static Library
@@ -147,6 +149,7 @@ if( QDLDL_BUILD_STATIC_LIB )
     # Declare include directories for the cmake exported target
     target_include_directories(qdldlstatic
                                PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
+                                      "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>"
                                       "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/${CMAKE_INSTALL_INCLUDEDIR}/qdldl>")
 
     # Install Static Library
@@ -182,7 +185,8 @@ if( QDLDL_BUILD_SHARED_LIB )
     # Declare include directories for the cmake exported target
     target_include_directories(qdldl
         PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
-        "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/${CMAKE_INSTALL_INCLUDEDIR}/qdldl>")
+               "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>"
+               "$<INSTALL_INTERFACE:$<INSTALL_PREFIX>/${CMAKE_INSTALL_INCLUDEDIR}/qdldl>")
 
     # Install qdldl shared library
     install(TARGETS qdldl