Fix Windows build

Change-Id: I145d220c73313e31c184b6a75ab7f4823df99919
Signed-off-by: Robert Hughes <robert.hughes@arm.com>
diff --git a/cmake/GlobalConfig.cmake b/cmake/GlobalConfig.cmake
index e5a5866..b093e5d 100644
--- a/cmake/GlobalConfig.cmake
+++ b/cmake/GlobalConfig.cmake
@@ -347,7 +347,7 @@
 
 # This is the root for the dynamic backend tests to search for dynamic
 # backends. By default it will be the project build directory.
-add_definitions('-DDYNAMIC_BACKEND_BUILD_DIR="${PROJECT_BINARY_DIR}"')
+add_definitions(-DDYNAMIC_BACKEND_BUILD_DIR="${PROJECT_BINARY_DIR}")
 
 # ArmNN dynamic backend
 if(DYNAMIC_BACKEND_PATHS)