add -fno-finite-math-only in KOPT_CFLAGS

In some compilation platform if finite-math-only option is turned
on, math functions like exp and sqrt will be dynamically linked to
finite versions which cannot be located in Kindle's GLIBC. In my
toolchain the symbol __exp_finite cannot be found in GLIBC_2.4 so
gcc just use __exp_finite in GLIBC_2.15, which will cause a run time
error in Kindle saying "version GLIBC_2.15 not found"

Makefile

@@ -36,7 +36,7 @@ HOSTAR:=ar
 
 # Base CFLAGS, without arch. We'll need it for luajit, because its Makefiles do some tricky stuff to differentiate HOST/TARGET
 BASE_CFLAGS:=-O2 -ffast-math -pipe
-KOPT_CFLAGS:=-O3 -ffast-math -pipe
+KOPT_CFLAGS:=-O3 -ffast-math -fno-finite-math-only -pipe
 # Use this for debugging:
 #BASE_CFLAGS:=-O0 -g
 # Misc GCC tricks to ensure backward compatibility with the K2, even when using a fairly recent TC (Linaro/MG).