Revert changes in libunwind vendor directory (#82473)

src/native/external/libunwind/src/CMakeLists.txt

@@ -326,38 +326,6 @@ SET(libunwind_loongarch64_la_SOURCES_loongarch
 	loongarch64/Gis_signal_frame.c loongarch64/Gregs.c loongarch64/Gresume.c loongarch64/Gstep.c
 )
 
-# The list of files that go into libunwind and libunwind-riscv:
-SET(libunwind_la_SOURCES_riscv_common
-    ${libunwind_la_SOURCES_common}
-    riscv/is_fpreg.c
-    riscv/regname.c
-)
-
-# The list of files that go into libunwind:
-SET(libunwind_la_SOURCES_riscv
-    ${libunwind_la_SOURCES_riscv_common}
-    ${libunwind_la_SOURCES_local}
-    riscv/setcontext.S
-    riscv/Lapply_reg_state.c riscv/Lreg_states_iterate.c
-    riscv/Lcreate_addr_space.c riscv/Lget_proc_info.c
-    riscv/Lget_save_loc.c riscv/Lglobal.c riscv/Linit.c
-    riscv/Linit_local.c riscv/Linit_remote.c
-    riscv/Lis_signal_frame.c riscv/Lregs.c riscv/Lresume.c
-    riscv/Lstep.c riscv/getcontext.S
-)
-
-SET(libunwind_riscv_la_SOURCES_riscv
-    ${libunwind_la_SOURCES_riscv_common}
-    ${libunwind_la_SOURCES_generic}
-    riscv/Gapply_reg_state.c riscv/Greg_states_iterate.c
-    riscv/Gcreate_addr_space.c riscv/Gget_proc_info.c
-    riscv/Gget_save_loc.c riscv/Gglobal.c riscv/Ginit.c
-    riscv/Ginit_local.c riscv/Ginit_remote.c
-    riscv/Gis_signal_frame.c riscv/Gregs.c riscv/Gresume.c
-    riscv/Gstash_frame.c riscv/Gstep.c
-)
-
-
 if(TARGET_AARCH64)
     SET(libunwind_la_SOURCES                    ${libunwind_la_SOURCES_aarch64})
     SET(libunwind_remote_la_SOURCES             ${libunwind_aarch64_la_SOURCES_aarch64})
@@ -381,11 +349,6 @@ elseif(TARGET_LOONGARCH64)
     SET(libunwind_la_SOURCES                    ${libunwind_la_SOURCES_loongarch64})
     SET(libunwind_remote_la_SOURCES             ${libunwind_loongarch64_la_SOURCES_loongarch})
     SET(libunwind_elf_la_SOURCES                ${libunwind_elf64_la_SOURCES})
-elseif(TARGET_RISCV)
-    SET(libunwind_la_SOURCES                    ${libunwind_la_SOURCES_riscv})
-    SET(libunwind_remote_la_SOURCES             ${libunwind_riscv_la_SOURCES_riscv})
-    SET(libunwind_elf_la_SOURCES                ${libunwind_elf64_la_SOURCES})
-    list(APPEND libunwind_setjmp_la_SOURCES     riscv/siglongjmp.S)
 endif()
 
 add_library(libunwind