[libclc] Fix recent merge issues (#16962)

* Clean up unnecessary CLC files
* Fix signed char issues in libspirv
* Align headers with upstream

Author: frasercrmck

libclc/clc/include/clc/common/unary_def.inc

@@ -113,6 +113,7 @@ _CLC_OVERLOAD _CLC_DEF ulong __clc_mul_hi(ulong x, ulong y) {
 
 #define __CLC_MUL_HI_TYPES()                                                   \
   __CLC_MUL_HI_DEC_IMPL(short, char, 8)                                        \
+  __CLC_MUL_HI_DEC_IMPL(short, schar, 8)                                       \
   __CLC_MUL_HI_DEC_IMPL(ushort, uchar, 8)                                      \
   __CLC_MUL_HI_DEC_IMPL(int, short, 16)                                        \
   __CLC_MUL_HI_DEC_IMPL(uint, ushort, 16)                                      \

libclc/clc/lib/generic/integer/clc_mul_hi.cl

@@ -38,21 +38,8 @@
 
 #include <core/convert.h>
 
-#include <core/integer/clc_abs.h>
-#include <core/integer/clc_abs_diff.h>
 #include <core/integer/clc_add_sat.h>
-#include <core/integer/clc_hadd.h>
-#include <core/integer/clc_mad24.h>
-#include <core/integer/clc_mad_hi.h>
 #include <core/integer/clc_mad_sat.h>
-#include <core/integer/clc_mul24.h>
-#include <core/integer/clc_mul_hi.h>
-#include <core/integer/clc_rhadd.h>
 #include <core/integer/clc_sub_sat.h>
-#include <core/integer/clc_upsample.h>
-
-#include <core/shared/clc_clamp.h>
-#include <core/shared/clc_max.h>
-#include <core/shared/clc_min.h>
 
 #pragma OPENCL EXTENSION all : disable