Try to use standard way to import gflags.

* See [here](https://gflags.github.io/gflags/#cmake).

CMakeLists.txt

@@ -26,7 +26,7 @@ find_package(NumPy REQUIRED)
 find_package(Threads REQUIRED)
 find_package(AVX QUIET)
 find_package(Glog REQUIRED)
-find_package(Gflags REQUIRED)
+find_package(gflags REQUIRED)
 find_package(GTest)
 find_package(Sphinx)
 find_package(Doxygen)

cmake/util.cmake

@@ -110,8 +110,8 @@ function(link_paddle_exe TARGET_NAME)
         ${METRIC_LIBS}
         ${PROTOBUF_LIBRARY}
         ${LIBGLOG_LIBRARY}
-        ${GFLAGS_LIBRARIES}
-        ${CMAKE_THREAD_LIBS_INIT}
+        gflags
+	${CMAKE_THREAD_LIBS_INIT}
         ${CBLAS_LIBS}
         ${ZLIB_LIBRARIES}
         ${INTERAL_LIBS}

paddle/api/paddle_ld_flags.py

@@ -50,7 +50,6 @@ try:
             self.glog_libs = LIBGLOG_LIBRARY
 
             self.with_coverage = PaddleLDFlag.cmake_bool(WITH_COVERALLS)
-            self.gflags_libs = GFLAGS_LIBRARIES
             self.gflags_location = GFLAGS_LOCATION
             self.cblas_libs = CBLAS_LIBRARIES
             self.curt = CUDA_LIBRARIES
@@ -88,7 +87,7 @@ try:
                 "-lpaddle_api",
                 self.normalize_flag(self.protolib),
                 self.normalize_flag(self.glog_libs),
-                self.normalize_flag(self.gflags_libs),
+                self.normalize_flag("gflags"),
                 self.normalize_flag(self.zlib),
                 self.normalize_flag(self.thread),
                 self.normalize_flag(self.dl_libs),
@@ -114,10 +113,7 @@ try:
                 return cmake_flag
             elif cmake_flag.startswith("-l"):  # normal link command
                 return cmake_flag
-            elif cmake_flag in [
-                    "gflags-shared", "gflags-static", "gflags_nothreads-shared",
-                    "gflags_nothreads-static"
-            ]:  # special for gflags
+            elif cmake_flag == "gflags":  # special for gflags
                 assert PaddleLDFlag.cmake_bool(self.gflags_location)
                 return self.gflags_location
             elif len(cmake_flag) != 0: