Add no-FPU ColdFire math_private.h.

As with some other soft-float configurations, no-FPU ColdFire needs
various fenv.h functions and glibc-internal macros overridden in
math_private.h to avoid references to undefined FE_* macros when
building glibc.  This patch adds a suitable math_private.h, based on
the MicroBlaze one (Nios II and Tile also have similar files).

There's a case for having such a file in sysdeps/ieee754/soft-fp so
this logic is applied more generally to configurations without
exceptions and rounding modes, even when the relevant macros are
defined in fenv.h - the only case where that might be inappropriate is
ARM soft-float (where the fenv.h functions might or might not work at
runtime, depending on whether the processor used at runtime supports
VFP).  There's also a case that soft-float configurations (on
processors with both hard-float and soft-float) should more
consistently avoid defining FE_* macros in bits/fenv.h when not
actually supported.  But both of those are separate potential
cleanups.

This allows the no-FPU ColdFire build to get further (another fix is
needed to allow the build to complete).

	* sysdeps/m68k/coldfire/nofpu/math_private.h: New file.  Based on
	MicroBlaze file.

ChangeLog

@@ -1,5 +1,8 @@
 2018-01-24  Joseph Myers  <joseph@codesourcery.com>
 
+	* sysdeps/m68k/coldfire/nofpu/math_private.h: New file.  Based on
+	MicroBlaze file.
+
 	* sysdeps/unix/sysv/linux/m68k/coldfire/jmp_buf-macros.h: Move to
 	....
 	* sysdeps/unix/sysv/linux/m68k/coldfire/fpu/jmp_buf-macros.h:

sysdeps/m68k/coldfire/nofpu/math_private.h

@@ -0,0 +1,52 @@
+/* Disable use of exceptions and rounding modes for no-FPU ColdFire.
+   Copyright (C) 2012-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef COLDFIRE_NOFPU_MATH_PRIVATE_H
+#define COLDFIRE_NOFPU_MATH_PRIVATE_H 1
+
+/* Suppress use of exceptions and rounding modes here to avoid build
+   errors if the FE_* macros aren't defined.
+
+   We intentionally ignore the "exception" arguments of functions that
+   take an exception, since we can't even evaluate the argument
+   without causing a build failure.  The extra level of statement
+   expression wrapping avoids "statement with no effect" warnings.
+   Since the callers don't check for errors anyway, we just claim
+   success in every case.
+
+   The overrides for libc_ functions must happen before we include
+   the generic math_private.h, and the overrides for regular
+   <fenv.h> functions must happen afterwards, to avoid clashing with
+   the declarations of those functions.  */
+
+#define libc_fesetround(rnd)                   ({ 0; })
+#define libc_fetestexcept(exc)                 ({ 0; })
+#define libc_feholdexcept_setround(env, exc)   ({ (void) (env); 0; })
+#define libc_feupdateenv_test(env, exc)        ({ (void) (env); 0; })
+
+/* Enable __finitel, __isinfl, and __isnanl for binary compatibility
+   when built without long double support. */
+#define LDBL_CLASSIFY_COMPAT 1
+
+#include_next <math_private.h>
+
+#define feraiseexcept(excepts)                 ({ 0; })
+#define __feraiseexcept(excepts)               ({ 0; })
+#define feclearexcept(exc)                     ({ 0; })
+
+#endif