Bug 1656155 - pt 4. Update size class fields in jemalloc_stats_t r=glandium

Previously there was one field here named small_max, and it wasn't obvious
from the name alone whether this meant the end of the
quantum-spaced sizes or the subpage sizes.  Instead place both these fields
into the structure with clearer names.  Besides, a later page will need
subpage_max.

Differential Revision: https://phabricator.services.mozilla.com/D88402

memory/build/mozjemalloc.cpp

@@ -4250,7 +4250,7 @@ inline void MozJemalloc::jemalloc_stats_internal(
   aStats->opt_junk = opt_junk;
   aStats->opt_zero = opt_zero;
   aStats->quantum = kQuantum;
-  aStats->small_max = kMaxQuantumClass;
+  aStats->quantum_max = kMaxQuantumClass;
   aStats->large_max = gMaxLargeClass;
   aStats->chunksize = kChunkSize;
   aStats->page_size = gPageSize;

memory/build/mozjemalloc_types.h

@@ -75,11 +75,12 @@ typedef struct arena_params_s {
 // file.
 typedef struct {
   // Run-time configuration settings.
-  bool opt_junk;     // Fill allocated memory with kAllocJunk?
-  bool opt_zero;     // Fill allocated memory with 0x0?
-  size_t narenas;    // Number of arenas.
-  size_t quantum;    // Allocation quantum.
-  size_t small_max;  // Max quantum-spaced allocation size.
+  bool opt_junk;       // Fill allocated memory with kAllocJunk?
+  bool opt_zero;       // Fill allocated memory with 0x0?
+  size_t narenas;      // Number of arenas.
+  size_t quantum;      // Allocation quantum.
+  size_t quantum_max;  // Max quantum-spaced allocation size.
+  // The next size class, sub-pagesize's max is always page_size/2.
   size_t large_max;  // Max sub-chunksize allocation size.
   size_t chunksize;  // Size of each virtual memory mapping.
   size_t page_size;  // Size of pages.