remove line continuation in cmake to adapt to cmake 2.x

CMakeLists.txt

@@ -6,8 +6,7 @@ option(DEBUG "Print debug logs" OFF)
 option(WITH_DEBUG_SYMBOLS "With debug symbols" ON)
 option(WITH_THRIFT "With thrift framed protocol supported" OFF)
 option(BUILD_UNIT_TESTS "Whether to build unit tests" OFF)
-option(DOWNLOAD_GTEST "Download and build a fresh copy of \
-                            googletest. Requires Internet access." ON)
+option(DOWNLOAD_GTEST "Download and build a fresh copy of googletest. Requires Internet access." ON)
 
 # Enable MACOSX_RPATH. Run "cmake --help-policy CMP0042" for policy details.
 if(POLICY CMP0042)