Use of != compare of floats in AttitudeEKF.c

This is a bug and is unsafe. I am not going to change the code but
it needs to be changed to a cast to int or a <= as it is unsafe to
check for equality with 0.0F.

Disabled warning for GCC 4.9 for now.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

makefiles/toolchain_native.mk

@@ -42,7 +42,7 @@
 #
 
 # Set to 1 for GCC-4.8.2 and to 0 for Clang-3.5 (Ubuntu 14.04)
-USE_GCC?=0
+USE_GCC?=1
 
 ifneq ($(USE_GCC),1)
 
@@ -193,7 +193,8 @@ ifeq ($(USE_GCC),1)
 ARCHCWARNINGS		+= -Wold-style-declaration \
 			   -Wmissing-parameter-type \
 			   -Wno-error=unused-local-typedefs \
-			   -Wno-error=enum-compare
+			   -Wno-error=enum-compare \
+			   -Wno-error=float-equal
 endif
 
 # C++-specific warnings