Fix UBSan warning in arithmetic decoder

Very similar to the ones that were fixed in the Huffman decoders in
8e9cef2e6f5156c4b055a04a8f979b7291fc6b7a.  These are innocuous.

Refer to https://bugzilla.mozilla.org/show_bug.cgi?id=1304567.
1 file changed
tree: 19371258fcd9f1885172390429d54bf5fc0a7dcf
  1. cmakescripts/
  2. doc/
  3. java/
  4. md5/
  5. release/
  6. sharedlib/
  7. simd/
  8. testimages/
  9. win/
  10. .gitignore
  11. acinclude.m4
  12. bmp.c
  13. bmp.h
  14. BUILDING.md
  15. cderror.h
  16. cdjpeg.c
  17. cdjpeg.h
  18. change.log
  19. ChangeLog.md
  20. cjpeg.1
  21. cjpeg.c
  22. CMakeLists.txt
  23. coderules.txt
  24. configure.ac
  25. djpeg.1
  26. djpeg.c
  27. doxygen-extra.css
  28. doxygen.config
  29. example.c
  30. jaricom.c
  31. jcapimin.c
  32. jcapistd.c
  33. jcarith.c
  34. jccoefct.c
  35. jccolext.c
  36. jccolor.c
  37. jcdctmgr.c
  38. jchuff.c
  39. jchuff.h
  40. jcinit.c
  41. jcmainct.c
  42. jcmarker.c
  43. jcmaster.c
  44. jcomapi.c
  45. jconfig.h.in
  46. jconfig.txt
  47. jconfigint.h.in
  48. jcparam.c
  49. jcphuff.c
  50. jcprepct.c
  51. jcsample.c
  52. jcstest.c
  53. jctrans.c
  54. jdapimin.c
  55. jdapistd.c
  56. jdarith.c
  57. jdatadst-tj.c
  58. jdatadst.c
  59. jdatasrc-tj.c
  60. jdatasrc.c
  61. jdcoefct.c
  62. jdcoefct.h
  63. jdcol565.c
  64. jdcolext.c
  65. jdcolor.c
  66. jdct.h
  67. jddctmgr.c
  68. jdhuff.c
  69. jdhuff.h
  70. jdinput.c
  71. jdmainct.c
  72. jdmainct.h
  73. jdmarker.c
  74. jdmaster.c
  75. jdmaster.h
  76. jdmerge.c
  77. jdmrg565.c
  78. jdmrgext.c
  79. jdphuff.c
  80. jdpostct.c
  81. jdsample.c
  82. jdsample.h
  83. jdtrans.c
  84. jerror.c
  85. jerror.h
  86. jfdctflt.c
  87. jfdctfst.c
  88. jfdctint.c
  89. jidctflt.c
  90. jidctfst.c
  91. jidctint.c
  92. jidctred.c
  93. jinclude.h
  94. jmemmgr.c
  95. jmemnobs.c
  96. jmemsys.h
  97. jmorecfg.h
  98. jpeg_nbits_table.h
  99. jpegcomp.h
  100. jpegint.h
  101. jpeglib.h
  102. jpegtran.1
  103. jpegtran.c
  104. jquant1.c
  105. jquant2.c
  106. jsimd.h
  107. jsimd_none.c
  108. jsimddct.h
  109. jstdhuff.c
  110. jutils.c
  111. jversion.h
  112. libjpeg.map.in
  113. libjpeg.txt
  114. LICENSE.md
  115. Makefile.am
  116. rdbmp.c
  117. rdcolmap.c
  118. rdgif.c
  119. rdjpgcom.1
  120. rdjpgcom.c
  121. rdppm.c
  122. rdrle.c
  123. rdswitch.c
  124. rdtarga.c
  125. README.ijg
  126. README.md
  127. structure.txt
  128. tjbench.c
  129. tjbenchtest.in
  130. tjbenchtest.java.in
  131. tjexampletest.in
  132. tjunittest.c
  133. tjutil.c
  134. tjutil.h
  135. transupp.c
  136. transupp.h
  137. turbojpeg-jni.c
  138. turbojpeg-mapfile
  139. turbojpeg-mapfile.jni
  140. turbojpeg.c
  141. turbojpeg.h
  142. usage.txt
  143. wizard.txt
  144. wrbmp.c
  145. wrgif.c
  146. wrjpgcom.1
  147. wrjpgcom.c
  148. wrppm.c
  149. wrppm.h
  150. wrrle.c
  151. wrtarga.c