spirv-opt: Remove unused folding rule (#4942)

diff --git a/source/opt/const_folding_rules.cpp b/source/opt/const_folding_rules.cpp
index cb36087..0ad755c 100644
--- a/source/opt/const_folding_rules.cpp
+++ b/source/opt/const_folding_rules.cpp
@@ -74,7 +74,7 @@
 
 // Returns a constants with the value |-val| of the given type.  Only works for
 // 32-bit and 64-bit float point types.  Returns |nullptr| if an error occurs.
-const analysis::Constant* negateFPConst(const analysis::Type* result_type,
+const analysis::Constant* NegateFPConst(const analysis::Type* result_type,
                                         const analysis::Constant* val,
                                         analysis::ConstantManager* const_mgr) {
   const analysis::Float* float_type = result_type->AsFloat();
@@ -755,7 +755,7 @@
   }
 
   if (numerator->AsFloatConstant()->GetValueAsDouble() < 0.0) {
-    result = negateFPConst(result_type, result, const_mgr);
+    result = NegateFPConst(result_type, result, const_mgr);
   }
   return result;
 }
@@ -780,7 +780,7 @@
     const analysis::Constant* result =
         FoldFPScalarDivideByZero(result_type, numerator, const_mgr);
     if (result != nullptr)
-      result = negateFPConst(result_type, result, const_mgr);
+      result = NegateFPConst(result_type, result, const_mgr);
     return result;
   } else {
     return FOLD_FPARITH_OP(/)(result_type, numerator, denominator, const_mgr);
@@ -951,7 +951,7 @@
             analysis::ConstantManager* const_mgr) -> const analysis::Constant* {
     assert(result_type != nullptr && a != nullptr);
     assert(result_type == a->type());
-    return negateFPConst(result_type, a, const_mgr);
+    return NegateFPConst(result_type, a, const_mgr);
   };
 }
 
@@ -1183,17 +1183,6 @@
   };
 }
 
-template <class IntType>
-IntType FoldIClamp(IntType x, IntType min_val, IntType max_val) {
-  if (x < min_val) {
-    x = min_val;
-  }
-  if (x > max_val) {
-    x = max_val;
-  }
-  return x;
-}
-
 const analysis::Constant* FoldMin(const analysis::Type* result_type,
                                   const analysis::Constant* a,
                                   const analysis::Constant* b,