newlib: remove unused fenv flags

These look like they were just copied & pasted from common/Makefile.am.
The funcs in this dir are all stubs that don't actually call any math
or builtin functions, and a simple compile shows they produce identical
object code.  So delete to simplify the build rules.

newlib/libm/fenv/Makefile.am

@@ -6,11 +6,9 @@ src =	feclearexcept.c fe_dfl_env.c fegetenv.c fegetexceptflag.c \
 	fegetround.c feholdexcept.c feraiseexcept.c fesetenv.c \
 	fesetexceptflag.c fesetround.c fetestexcept.c feupdateenv.c
 
-lib_a_CFLAGS = -fbuiltin -fno-math-errno
-
 noinst_LIBRARIES = lib.a
 lib_a_SOURCES = $(src)
-lib_a_CFLAGS += $(AM_CFLAGS)
+lib_a_CFLAGS = $(AM_CFLAGS)
 
 # A partial dependency list.
 

newlib/libm/fenv/Makefile.in

@@ -302,9 +302,9 @@ src = feclearexcept.c fe_dfl_env.c fegetenv.c fegetexceptflag.c \
 	fegetround.c feholdexcept.c feraiseexcept.c fesetenv.c \
 	fesetexceptflag.c fesetround.c fetestexcept.c feupdateenv.c
 
-lib_a_CFLAGS = -fbuiltin -fno-math-errno $(AM_CFLAGS)
 noinst_LIBRARIES = lib.a
 lib_a_SOURCES = $(src)
+lib_a_CFLAGS = $(AM_CFLAGS)
 all: all-am
 
 .SUFFIXES: