COMPMID-2486: Remove/add disabled compiler warnings

Removed the following flags:
-Wno-vla
-Wno-strict-overflow

Added:
-Wformat-security

Change-Id: I49eb3d724e14db796e543164295674617c37cb65
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/2109
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
diff --git a/SConstruct b/SConstruct
index 83eb7e0..8509fed 100644
--- a/SConstruct
+++ b/SConstruct
@@ -132,8 +132,8 @@
 env.Append(CXXFLAGS = ['-Wall','-DARCH_ARM',
          '-Wextra','-pedantic','-Wdisabled-optimization','-Wformat=2',
          '-Winit-self','-Wstrict-overflow=2','-Wswitch-default',
-         '-fpermissive','-std=gnu++11','-Wno-vla','-Woverloaded-virtual',
-         '-Wctor-dtor-privacy','-Wsign-promo','-Weffc++','-Wno-overlength-strings','-Wno-strict-overflow'])
+         '-fpermissive','-std=gnu++11','-Woverloaded-virtual', '-Wformat-security',
+         '-Wctor-dtor-privacy','-Wsign-promo','-Weffc++','-Wno-overlength-strings'])
 
 env.Append(CPPDEFINES = ['_GLIBCXX_USE_NANOSLEEP'])