[libc][NFC] remove completed TODOs

[michaelrj]

Summary

There were some "TODO" messages that were for things that I have already
completed. This patch removes those.

libc/src/__support/str_to_float.h

 #include "src/__support/high_precision_decimal.h"
 #include "src/__support/str_to_integer.h"
 #include <errno.h>
 
 namespace __llvm_libc {
 namespace internal {
 
 template <class T> uint32_t inline leading_zeroes(T inputNumber) {
-  // TODO(michaelrj): investigate the portability of using something like
-  // __builtin_clz for specific types.
   constexpr uint32_t BITS_IN_T = sizeof(T) * 8;
   if (inputNumber == 0) {
     return BITS_IN_T;
   }
   uint32_t cur_guess = BITS_IN_T / 2;
   uint32_t range_size = BITS_IN_T / 2;
   // while either shifting by curGuess does not get rid of all of the bits or
   // shifting by one less also gets rid of all of the bits then we have not

libc/test/src/__support/str_to_float_test.cpp

TEST(LlvmLibcStrToFloatTest, SimpleDecimalConversionExtraTypes) {
   output_exp2 = 0;
 
   errno = 0;
   __llvm_libc::internal::simple_decimal_conversion<double>(
       "123456789012345678900", &double_output_mantissa, &output_exp2);
   EXPECT_EQ(double_output_mantissa, uint64_t(0x1AC53A7E04BCDA));
   EXPECT_EQ(output_exp2, uint32_t(1089));
   EXPECT_EQ(errno, 0);
-
-  // TODO(michaelrj): Get long double support working.
-
-  // __uint128_t longDoubleOutputMantissa = 0;
-  // outputExp2 = 0;
-
-  // errno = 0;
-  // __llvm_libc::internal::simple_decimal_conversion<long double>(
-  //     "123456789012345678900", &longDoubleOutputMantissa, &outputExp2);
-  // EXPECT_EQ(longDoubleOutputMantissa, __uint128_t(0x1AC53A7E04BCDA));
-  // EXPECT_EQ(outputExp2, uint32_t(1089));
-  // EXPECT_EQ(errno, 0);
 }
 
 #if defined(LONG_DOUBLE_IS_DOUBLE)
 TEST_F(LlvmLibcStrToFloatTest, EiselLemireFloat64AsLongDouble) {
   eisel_lemire_test<long double>(123, 0, 0x1EC00000000000, 1029);
 }
 #elif defined(SPECIAL_X86_LONG_DOUBLE)
 TEST_F(LlvmLibcStrToFloatTest, EiselLemireFloat80Simple) {