[runtimes] NFCI: Drop intermediate CMake variable TARGET_TRIPLE

We might as well use the various XXX_TARGET_TRIPLE variables directly.

GitOrigin-RevId: 77396bbc981a96e22eae9f0bc79a7d55316501c1
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9eada68..68fb07c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -167,10 +167,6 @@
   set(LIBUNWIND_SYSROOT "${CMAKE_SYSROOT}")
 endif()
 
-if (LIBUNWIND_TARGET_TRIPLE)
-  set(TARGET_TRIPLE "${LIBUNWIND_TARGET_TRIPLE}")
-endif()
-
 # Configure compiler.
 include(config-ix)
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 5be44e5..b2cc95d 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -36,8 +36,8 @@
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
-if (TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${TARGET_TRIPLE}\"")
+if (LIBUNWIND_TARGET_TRIPLE)
+  serialize_lit_param(target_triple "\"${LIBUNWIND_TARGET_TRIPLE}\"")
 endif()
 
 if (LIBUNWIND_BUILD_32_BITS)