Change loop counter to unsigned to fix a spurious gcc-13 warning (#7314)

It seems to think that the row counter somehow can have any negative
value, but I couldn't find a way for that to happen.

tsl/src/nodes/vector_agg/function/float48_accum_single.c

@@ -194,7 +194,7 @@ FUNCTION_NAME(combine)(double *inout_N, double *inout_Sx,
 #endif
 
 static pg_attribute_always_inline void
-FUNCTION_NAME(vector_impl)(void *agg_state, int n, const CTYPE *values, const uint64 *valid1,
+FUNCTION_NAME(vector_impl)(void *agg_state, size_t n, const CTYPE *values, const uint64 *valid1,
  const uint64 *valid2, MemoryContext agg_extra_mctx)
 {
  /*
@@ -212,15 +212,15 @@ FUNCTION_NAME(vector_impl)(void *agg_state, int n, const CTYPE *values, const ui
  double Sxxarray[UNROLL_SIZE] = { 0 };
 #endif
 
- int row = 0;
+ size_t row = 0;
 
 #ifdef NEED_SXX
  /*
  * Initialize each state with the first matching row. We do this separately
  * to make the actual update function branchless, namely the computation of
  * Sxx which works differently for the first row.
  */
- for (int inner = 0; inner < UNROLL_SIZE; inner++)
+ for (size_t inner = 0; inner < UNROLL_SIZE; inner++)
  {
  for (; row < n; row++)
  {
@@ -240,7 +240,8 @@ FUNCTION_NAME(vector_impl)(void *agg_state, int n, const CTYPE *values, const ui
  * Scroll to the row that is a multiple of UNROLL_SIZE. This is the correct
  * row at which to enter the unrolled loop below.
  */
- for (int inner = row % UNROLL_SIZE; inner > 0 && inner < UNROLL_SIZE && row < n; inner++, row++)
+ for (size_t inner = row % UNROLL_SIZE; inner > 0 && inner < UNROLL_SIZE && row < n;
+ inner++, row++)
  {
  UPDATE(valid1, valid2, values, row, &Narray[inner], &Sxarray[inner], &Sxxarray[inner]);
  }
@@ -252,7 +253,7 @@ FUNCTION_NAME(vector_impl)(void *agg_state, int n, const CTYPE *values, const ui
  Assert(row % UNROLL_SIZE == 0 || row == n);
  for (; row < UNROLL_SIZE * (n / UNROLL_SIZE); row += UNROLL_SIZE)
  {
- for (int inner = 0; inner < UNROLL_SIZE; inner++)
+ for (size_t inner = 0; inner < UNROLL_SIZE; inner++)
  {
  UPDATE(valid1,
  valid2,
@@ -269,7 +270,7 @@ FUNCTION_NAME(vector_impl)(void *agg_state, int n, const CTYPE *values, const ui
  */
  for (; row < n; row++)
  {
- const int inner = row % UNROLL_SIZE;
+ const size_t inner = row % UNROLL_SIZE;
  UPDATE(valid1, valid2, values, row, &Narray[inner], &Sxarray[inner], &Sxxarray[inner]);
  }