CMakeLists.txt: Some fixes for Relocatable package (#179)

There are some absolute path in the generation of the .cmake files
which ruin the creation of relocatable packages.
Fixing:
 * CMAKE_MODULE_PATH append instead of replacement
 * INTERFACE use relative path instead of ${CMAKE_INSTALL_INCLUDEDIR}

See also

https://cmake.org/cmake/help/latest/guide/importing-exporting/index.html#creating-relocatable-packages

for reference.

Signed-off-by: Matthias Schoepfer <[email protected]>
Co-authored-by: Matthias Schoepfer <[email protected]>

CMakeLists.txt

@@ -43,7 +43,7 @@ if(MSVC OR MSVC90 OR MSVC10)
   set(MSVC ON)
 endif (MSVC OR MSVC90 OR MSVC10)
 
-set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 
 find_package(tinyxml2_vendor QUIET)
 find_package(TinyXML2 REQUIRED)

urdf_parser/CMakeLists.txt

@@ -75,9 +75,9 @@ target_include_directories(urdf_parser INTERFACE
   "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
   "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
 target_link_libraries(urdf_parser INTERFACE
-  urdfdom_model
-  urdfdom_sensor
-  urdfdom_world)
+  urdfdom::urdfdom_model
+  urdfdom::urdfdom_sensor
+  urdfdom::urdfdom_world)
 
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