Remove deprecated flags from spirv-opt help message (#4788)

* Remove deprecated `--decompose-initialized-variables` from spirv-opt help message

* Remove deprecated --strip-atomic-counter-memory flag from spirv-opt help message

tools/opt/opt.cpp

@@ -157,12 +157,6 @@ Options (in lexicographical order):)",
                another.  It will only propagate an array if the source is never
                written to, and the only store to the target is the copy.)");
   printf(R"(
-  --decompose-initialized-variables
-               Decomposes initialized variable declarations into a declaration
-               followed by a store of the initial value. This is done to work
-               around known issues with some Vulkan drivers for initialize
-               variables.)");
-  printf(R"(
   --replace-desc-array-access-using-var-index
                Replaces accesses to descriptor arrays based on a variable index
                with a switch that has a case for every possible value of the
@@ -491,9 +485,6 @@ Options (in lexicographical order):)",
   --strength-reduction
                Replaces instructions with equivalent and less expensive ones.)");
   printf(R"(
-  --strip-atomic-counter-memory
-               Removes AtomicCountMemory bit from memory semantics values.)");
-  printf(R"(
   --strip-debug
                Remove all debug instructions.)");
   printf(R"(