aarch64: Add HF routines to libgcc_s.so

The libgcc HF support routines were being linked into libgcc_s.so,
but weren't being exported.

libgcc/
	* config/aarch64/libgcc-softfp.ver: New file.
	* config/aarch64/t-softfp (SHLIB_MAPFILES): Add it.

libgcc/config/aarch64/libgcc-softfp.ver

@@ -0,0 +1,28 @@
+# Copyright (C) 2020 Free Software Foundation, Inc.
+#
+# This file is part of GCC.
+#
+# GCC is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GCC 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+GCC_11.0 {
+  __divhc3
+  __extendhftf2
+  __fixhfti
+  __fixunshfti
+  __floattihf
+  __floatuntihf
+  __mulhc3
+  __trunctfhf2
+}

libgcc/config/aarch64/t-softfp

@@ -8,3 +8,4 @@ softfp_extras := fixhfti fixunshfti floattihf floatuntihf
 TARGET_LIBGCC2_CFLAGS += -Wno-missing-prototypes
 
 LIB2ADD += $(srcdir)/config/aarch64/sfp-exceptions.c
+SHLIB_MAPFILES += $(srcdir)/config/aarch64/libgcc-softfp.ver