[gar/cmake] Fix include dirs

+ aligator general includes are PRIVATE
+ when building, gar includes themselves are public

Author: ManifoldFR

gar/CMakeLists.txt

@@ -11,7 +11,11 @@ file(
 )
 
 add_library(aligator_gar SHARED)
-target_include_directories(aligator_gar PRIVATE ${PROJECT_SOURCE_DIR}/include/aligator)
+target_include_directories(
+  aligator_gar
+  PRIVATE ${PROJECT_SOURCE_DIR}/include
+  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include>
+)
 target_link_libraries(aligator_gar PUBLIC proxsuite-nlp::proxsuite-nlp)
 if(BUILD_WITH_OPENMP_SUPPORT)
   target_link_libraries(aligator_gar PUBLIC OpenMP::OpenMP_CXX)