build, docs: fixes find_external_library header search paths and docs

Includes:
- search for headers in the library directory when using find_external_library
- prevent module processing (brite, click and openflow) from continuing if ${dependency_name}_FOUND is not set

build-support/macros-and-definitions.cmake

@@ -1305,8 +1305,7 @@ function(remove_lib_prefix prefixed_library library)
 
   # If there is a lib prefix, try to remove it
   if(${lib_pos} EQUAL 0)
-    # Check if we still have something remaining
-    # after removing the "lib" prefix
+    # Check if we still have something remaining after removing the "lib" prefix
     string(LENGTH ${prefixed_library} len)
     if(${len} LESS 4)
       message(FATAL_ERROR "Invalid library name: ${prefixed_library}")
@@ -1821,7 +1820,7 @@ function(find_external_library)
   foreach(libdir ${library_dirs})
     get_filename_component(parent_libdir ${libdir} DIRECTORY)
     get_filename_component(parent_parent_libdir ${parent_libdir} DIRECTORY)
-    list(APPEND parent_dirs ${parent_libdir} ${parent_parent_libdir})
+    list(APPEND parent_dirs ${libdir} ${parent_libdir} ${parent_parent_libdir})
   endforeach()
 
   # If we already found a library somewhere, limit the search paths for the

doc/manual/source/working-with-cmake.rst

@@ -814,7 +814,7 @@ Here is how it works:
     foreach(libdir ${library_dirs})
       get_filename_component(parent_libdir ${libdir} DIRECTORY)
       get_filename_component(parent_parent_libdir ${parent_libdir} DIRECTORY)
-      list(APPEND parent_dirs ${parent_libdir} ${parent_parent_libdir})
+      list(APPEND parent_dirs ${libdir} ${parent_libdir} ${parent_parent_libdir})
     endforeach()
 
     # If we already found a library somewhere, limit the search paths for the header
@@ -986,10 +986,16 @@ example of ``find_external_library`` usage.
       SEARCH_PATHS ${NS3_WITH_OPENFLOW} # user-settable search path, empty by default
     )
 
-    # Check if header and library were found, 
-    # and stop processing the module in case they were not
-    if(NOT
-      ${openflow_FOUND}
+    # Before testing if the header and library were found ${openflow_FOUND},
+    # test if openflow_FOUND was defined
+    # If openflow_FOUND was not defined, the dependency name above doesn't match
+    # the tested values below
+    # If openflow_FOUND is set to FALSE, stop processing the module by returning
+    # to the parent directory with return()
+    if((NOT
+        openflow_FOUND)
+       AND (NOT
+            ${openflow_FOUND})
     )
       message(STATUS "Openflow was not found")
       return()

src/brite/CMakeLists.txt

@@ -16,8 +16,10 @@ find_external_library(
   SEARCH_PATHS ${NS3_WITH_BRITE}
 )
 
-if(NOT
-   ${brite_FOUND}
+if((NOT
+    brite_FOUND)
+   OR (NOT
+       ${brite_FOUND})
 )
   message(STATUS "Skipping src/brite")
   return()

src/click/CMakeLists.txt

@@ -17,8 +17,10 @@ find_external_library(
   SEARCH_PATHS ${NS3_WITH_CLICK}
 )
 
-if(NOT
-   ${click_FOUND}
+if((NOT
+    click_FOUND)
+   AND (NOT
+        ${click_FOUND})
 )
   message(STATUS "Skipping src/click")
   return()

src/openflow/CMakeLists.txt

@@ -16,8 +16,10 @@ find_external_library(
   SEARCH_PATHS ${NS3_WITH_OPENFLOW}
 )
 
-if(NOT
-   ${openflow_FOUND}
+if((NOT
+    openflow_FOUND)
+   AND (NOT
+        ${openflow_FOUND})
 )
   message(STATUS "Skipping src/openflow")
   return()