newlib: fix mips fenv.o handling

Commit 8fa73a9f84 changed how fenv.c is
compiled wrt mips16 targets used the wrong variable to add fenv.o to
libm.a.  Fix that thinko so it's included in the build again.

newlib/libm/machine/mips/Makefile.am

@@ -11,7 +11,7 @@ noinst_LIBRARIES = lib.a
 lib_a_SOURCES = $(LIB_SOURCES)
 lib_a_CFLAGS = $(AM_CFLAGS)
 
-LIBADD_OBJS = \
+lib_a_LIBADD = \
 	lib_a-fenv.$(OBJEXT)
 
 # fenv.c cannot be compiled as mips16 since it uses the cfc1 instruction

newlib/libm/machine/mips/Makefile.in

@@ -111,7 +111,7 @@ am__v_AR_ = $(am__v_AR_@AM_DEFAULT_V@)
 am__v_AR_0 = @echo "  AR      " $@;
 am__v_AR_1 = 
 lib_a_AR = $(AR) $(ARFLAGS)
-lib_a_LIBADD =
+lib_a_DEPENDENCIES = lib_a-fenv.$(OBJEXT)
 am__objects_1 = lib_a-feclearexcept.$(OBJEXT) lib_a-fegetenv.$(OBJEXT) \
 	lib_a-fegetexceptflag.$(OBJEXT) lib_a-fegetround.$(OBJEXT) \
 	lib_a-feholdexcept.$(OBJEXT) lib_a-feraiseexcept.$(OBJEXT) \
@@ -305,7 +305,7 @@ LIB_SOURCES = \
 noinst_LIBRARIES = lib.a
 lib_a_SOURCES = $(LIB_SOURCES)
 lib_a_CFLAGS = $(AM_CFLAGS)
-LIBADD_OBJS = \
+lib_a_LIBADD = \
 	lib_a-fenv.$(OBJEXT)
 
 all: all-am