build: Fetch libs before bl2 stage

BL2 stage depends on path variables from library fetches.

Signed-off-by: Dávid Házi <david.hazi@arm.com>
Change-Id: I646168675d583d73033dc9e5e6da24b7f336eca8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1569ecb..3b91733 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -37,12 +37,14 @@
 
 project("Trusted Firmware M" VERSION ${TFM_VERSION} LANGUAGES C CXX ASM)
 
+add_subdirectory(lib/ext)
+
 if(BL2)
     add_subdirectory(bl2)
 endif()
 
 add_subdirectory(lib/backtrace)
-add_subdirectory(lib/ext)
+
 add_subdirectory(lib/fih)
 add_subdirectory(lib/tfm_log)
 add_subdirectory(lib/tfm_log_unpriv)