[libclc] Move rootn to the CLC library; optimize (#133735)

The function was already nominally in the CLC namespace; this commit
just moves it over.

This commit also vectorizes the builtin to avoid scalarization.

Author: frasercrmck

libclc/generic/include/math/clc_rootn.h renamed to libclc/clc/include/clc/math/clc_rootn.h

@@ -6,6 +6,15 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define __CLC_BODY <math/clc_rootn.inc>
+#ifndef __CLC_MATH_CLC_ROOTN_H__
+#define __CLC_MATH_CLC_ROOTN_H__
+
+#define __CLC_BODY <clc/math/binary_decl_with_int_second_arg.inc>
+#define __CLC_FUNCTION __clc_rootn
+
 #include <clc/math/gentype.inc>
+
 #undef __CLC_BODY
+#undef __CLC_FUNCTION
+
+#endif // __CLC_MATH_CLC_ROOTN_H__

libclc/clc/lib/generic/SOURCES

@@ -52,6 +52,7 @@ math/clc_powr.cl
 math/clc_remainder.cl
 math/clc_remquo.cl
 math/clc_rint.cl
+math/clc_rootn.cl
 math/clc_round.cl
 math/clc_rsqrt.cl
 math/clc_sincos_helpers.cl

libclc/clc/lib/generic/math/clc_rootn.cl

@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <clc/clc_convert.h>
+#include <clc/float/definitions.h>
+#include <clc/internal/clc.h>
+#include <clc/math/clc_fabs.h>
+#include <clc/math/clc_fma.h>
+#include <clc/math/clc_ldexp.h>
+#include <clc/math/clc_mad.h>
+#include <clc/math/clc_subnormal_config.h>
+#include <clc/math/math.h>
+#include <clc/math/tables.h>
+
+#define __CLC_BODY <clc_rootn.inc>
+#include <clc/math/gentype.inc>