[llvm][CMake] Remove -fno-lifetime-dse (#173322)

Now that #24952 has been fixed by #170575, we no longer need to specify
-fno-lifetime-dse when building with gcc.

Author: boomanaiden154

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -713,16 +713,6 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   append("-Werror=unguarded-availability-new" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif()
 
-if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND LLVM_ENABLE_LTO)
-  # LLVM data structures like llvm::User and llvm::MDNode rely on
-  # the value of object storage persisting beyond the lifetime of the
-  # object (#24952).  This is not standard compliant and causes a runtime
-  # crash if LLVM is built with GCC and LTO enabled (#57740).  Until
-  # these bugs are fixed, we need to disable dead store eliminations
-  # based on object lifetime.
-  append("-fno-lifetime-dse" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
-endif ()
-
 # Modules enablement for GCC-compatible compilers:
 if ( LLVM_COMPILER_IS_GCC_COMPATIBLE AND LLVM_ENABLE_MODULES )
   set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})