Hexagon HVX (target/hexagon) instruction utility functions

Functions to support scatter/gather
Add new file to target/hexagon/meson.build

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>

target/hexagon/mmvec/system_ext_mmvec.h

@@ -0,0 +1,25 @@
+/*
+ *  Copyright(c) 2019-2021 Qualcomm Innovation Center, Inc. All Rights Reserved.
+ *
+ *  This program 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 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HEXAGON_SYSTEM_EXT_MMVEC_H
+#define HEXAGON_SYSTEM_EXT_MMVEC_H
+
+void mem_gather_store(CPUHexagonState *env, target_ulong vaddr, int slot);
+void mem_vector_scatter_init(CPUHexagonState *env);
+void mem_vector_gather_init(CPUHexagonState *env);
+
+#endif