Replace tabs with spaces

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6133d07..4dbe76e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,8 @@
 cmake_minimum_required(VERSION 2.6)
 if(TEST_CPP)
-	project("mbed TLS" C CXX)
+    project("mbed TLS" C CXX)
 else()
-	project("mbed TLS" C)
+    project("mbed TLS" C)
 endif()
 
 option(USE_PKCS11_HELPER_LIBRARY "Build mbed TLS with the pkcs11-helper library." OFF)