rts: fix small argument passing on big-endian arch (fix #23387)
Fix #23387 (closed) (failure in GHCiPrimCall on big-endian architectures) by storing small arguments into the high part of the words on the stack.
It also changed the result of the LargeBCO
test, which is still failing:
Before this MR:
-SHA256S 1251949539 2800197164 2023110800 2630081144 3831421046 3141654527 2982319529 2535435789
+SHA256S 0 0 0 0 0 0 0 0
After the fix for GHCiPrimCall:
-SHA256S 1251949539 2800197164 2023110800 2630081144 3831421046 3141654527 2982319529 2535435789
+SHA256S 1543507840 1892255834 1874519280 1874519280 1874519280 1891727560 1874517840 11