Fix FindNCCL.cmake

Fix search paths for headers and libs

Use NCCL_LIBRARY instead of NCCL_LIBRARIES
  - stylistic, matches Simon's code

Author: lukeyeager

cmake/Dependencies.cmake

@@ -184,5 +184,5 @@ endif()
 if(NCCL_FOUND)
   add_definitions(-DUSE_NCCL)
   include_directories(SYSTEM ${NCCL_INCLUDE})
-  list(APPEND Caffe_LINKER_LIBS ${NCCL_LIBRARIES})
+  list(APPEND Caffe_LINKER_LIBS ${NCCL_LIBRARY})
 endif()

cmake/Modules/FindNCCL.cmake

@@ -6,17 +6,20 @@
 # The following are set after configuration is done:
 #  NCCL_FOUND
 #  NCCL_INCLUDE_DIR
-#  NCCL_LIBRARIES
+#  NCCL_LIBRARY
 
-find_path(NCCL_INCLUDE_DIR NAMES nccl.h PATHS ${NCCL_ROOT_DIR})
+find_path(NCCL_INCLUDE_DIR NAMES nccl.h
+    PATHS ${NCCL_ROOT_DIR}/include
+    )
 
-find_library(NCCL_LIBRARIES NAMES nccl PATHS ${NCCL_ROOT_DIR})
+find_library(NCCL_LIBRARY NAMES nccl
+    PATHS ${NCCL_ROOT_DIR}/lib ${NCCL_ROOT_DIR}/lib64)
 
 include(FindPackageHandleStandardArgs)
-find_package_handle_standard_args(NCCL DEFAULT_MSG NCCL_INCLUDE_DIR NCCL_LIBRARIES)
+find_package_handle_standard_args(NCCL DEFAULT_MSG NCCL_INCLUDE_DIR NCCL_LIBRARY)
 
 if(NCCL_FOUND)
-  message(STATUS "Found NCCL (include: ${NCCL_INCLUDE_DIR}, library: ${NCCL_LIBRARIES})")
-  mark_as_advanced(NCCL_INCLUDE_DIR NCCL_LIBRARIES)
+  message(STATUS "Found NCCL (include: ${NCCL_INCLUDE_DIR}, library: ${NCCL_LIBRARY})")
+  mark_as_advanced(NCCL_INCLUDE_DIR NCCL_LIBRARY)
 endif()