cmake: Always build position independent code

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

cmake/Modules/DefineCMakeDefaults.cmake

@@ -16,3 +16,6 @@ set(CMAKE_COLOR_MAKEFILE ON)
 
 # Create the compile command database for clang by default
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Always build with -fPIC
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)