Bug 1553058 - Remove unused gPageSize case. r=njn

MALLOC_STATIC_PAGESIZE is only set on some platforms. Specifically, it's
not set on ia64 and sparc. Which means the case MALLOC_STATIC_PAGESIZE
&& (sparc || ia64) never happens, and gPageSize is never 8 KiB.

Differential Revision: https://phabricator.services.mozilla.com/D31965

--HG--
extra : moz-landing-system : lando

memory/build/mozjemalloc.cpp

@@ -420,10 +420,7 @@ static const size_t kChunkSizeMask = kChunkSize - 1;
 // VM page size. It must divide the runtime CPU page size or the code
 // will abort.
 // Platform specific page size conditions copied from js/public/HeapAPI.h
-#  if (defined(SOLARIS) || defined(__FreeBSD__)) && \
-      (defined(__sparc) || defined(__sparcv9) || defined(__ia64))
-static const size_t gPageSize = 8_KiB;
-#  elif defined(__powerpc64__)
+#  if defined(__powerpc64__)
 static const size_t gPageSize = 64_KiB;
 #  else
 static const size_t gPageSize = 4_KiB;