strict aliasing warnings on gcc10

[terrelln]

Describe the bug
gcc10 has new strict aliasing warnings not raised in gcc9.

To Reproduce

> CC=gcc10 make zstd
../lib/compress/zstd_compress.c: In function ‘ZSTD_loadCEntropy’:
../lib/compress/zstd_compress.c:2923:64: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
 2923 |         size_t const hufHeaderSize = HUF_readCTable((HUF_CElt*)bs->entropy.huf.CTable, &maxSymbolValue, dictPtr,
      |                                                                ^~
../lib/compress/zstd_compress_literals.c: In function ‘ZSTD_compressLiterals’:
../lib/compress/zstd_compress_literals.c:108:28: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  108 |                 (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2) :
      |                            ^~~~~~~
../lib/compress/zstd_compress_literals.c:112:28: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  112 |                 (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2);
      |                            ^~~~~~~
../lib/compress/zstd_compress_superblock.c: In function ‘ZSTD_buildSuperBlockEntropy_literal’:
../lib/compress/zstd_compress_superblock.c:116:76: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  116 |     if (repeat == HUF_repeat_check && !HUF_validateCTable((HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue)) {
      |                                                                            ^~~~~~~
../lib/compress/zstd_compress_superblock.c:123:64: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  123 |     {   size_t const maxBits = HUF_buildCTable_wksp((HUF_CElt*)nextHuf->CTable, countWksp,
      |                                                                ^~~~~~~
../lib/compress/zstd_compress_superblock.c:130:32: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  130 |                     (HUF_CElt*)nextHuf->CTable, countWksp, maxSymbolValue);
      |                                ^~~~~~~
../lib/compress/zstd_compress_superblock.c:133:32: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  133 |                     (HUF_CElt*)nextHuf->CTable, maxSymbolValue, huffLog);
      |                                ^~~~~~~
../lib/compress/zstd_compress_superblock.c:137:42: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  137 |                         (HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue);
      |                                          ^~~~~~~
../lib/compress/zstd_compress_superblock.c: In function ‘ZSTD_compressSubBlock’:
../lib/compress/zstd_compress_superblock.c:553:74: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  553 |     {   size_t cLitSize = ZSTD_compressSubBlock_literal((const HUF_CElt*)entropy->huf.CTable,
      |                                                                          ^~~~~~~
../lib/compress/zstd_compress_superblock.c: In function ‘ZSTD_estimateSubBlockSize_literal’:
../lib/compress/zstd_compress_superblock.c:594:83: warning: dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
  594 |         {   size_t cLitSizeEstimate = HUF_estimateCompressedSize((const HUF_CElt*)huf->CTable, countWksp, maxSymbolValue);
      |

Expected behavior
No warnings

Desktop (please complete the following information):

• Compiler gcc10

[terrelln]

Fixed by PR #2415