[RISCV] Install sifive_vector.h to riscv-resource-headers (#66330)

Author: 4vtomat

clang/lib/Headers/CMakeLists.txt

@@ -477,7 +477,7 @@ add_header_target("loongarch-resource-headers" "${loongarch_files}")
 add_header_target("mips-resource-headers" "${mips_msa_files}")
 add_header_target("ppc-resource-headers" "${ppc_files};${ppc_wrapper_files}")
 add_header_target("ppc-htm-resource-headers" "${ppc_htm_files}")
-add_header_target("riscv-resource-headers" "${riscv_files};${riscv_generated_files}")
+add_header_target("riscv-resource-headers" "${riscv_files};${riscv_generated_files};${sifive_files}")
 add_header_target("systemz-resource-headers" "${systemz_files}")
 add_header_target("ve-resource-headers" "${ve_files}")
 add_header_target("webassembly-resource-headers" "${webassembly_files}")
@@ -623,6 +623,11 @@ install(
   EXCLUDE_FROM_ALL
   COMPONENT riscv-resource-headers)
 
+install(
+  FILES ${sifive_files}
+  DESTINATION ${header_install_dir}
+  COMPONENT riscv-resource-headers)
+
 install(
   FILES ${systemz_files}
   DESTINATION ${header_install_dir}

clang/test/Headers/riscv-sifive-header.c

@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -triple riscv64 -target-feature +v %s
+// REQUIRES: riscv-registered-target
+
+// expected-no-diagnostics
+
+#include <sifive_vector.h>