Replace OPENCENSUS_INCLUDE_DIR with CMAKE_SOURCE_DIR. (#261)

The OPENCENSUS_INCLUDE_DIR alias isn't needed.

Author: meastp

CMakeLists.txt

@@ -25,13 +25,13 @@ project(opencensus-cpp VERSION 0.3.0 LANGUAGES CXX)
 
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(OPENCENSUS_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
 
 include(CTest) # Defines option BUILD_TESTING.
 enable_testing()
 
 list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
 include(OpenCensusDeps)
+
 include(OpenCensusHelpers)
 
 # OpenCensus code.

cmake/OpenCensusHelpers.cmake

@@ -47,11 +47,11 @@ function(opencensus_lib NAME)
   if(ARG_SRCS)
     add_library(${_NAME} ${ARG_SRCS})
     target_link_libraries(${_NAME} PUBLIC ${ARG_DEPS})
-    target_include_directories(${_NAME} PUBLIC ${OPENCENSUS_INCLUDE_DIR})
+    target_include_directories(${_NAME} PUBLIC ${CMAKE_SOURCE_DIR})
   else()
     add_library(${_NAME} INTERFACE)
     target_link_libraries(${_NAME} INTERFACE ${ARG_DEPS})
-    target_include_directories(${_NAME} INTERFACE ${OPENCENSUS_INCLUDE_DIR})
+    target_include_directories(${_NAME} INTERFACE ${CMAKE_SOURCE_DIR})
   endif()
   if(ARG_PUBLIC)
     add_library(${PROJECT_NAME}::${NAME} ALIAS ${_NAME})