[scudo][standalone] Revert some perf-degrading changes

[cryptoad]

Summary

A couple of seemingly innocuous changes ended up having a large impact
on the 32-bit performance. I still have to make those configurable at
some point, but right now it will have to do.

[merge_guards_bot]

Unit tests: pass. 62302 tests passed, 0 failed and 838 were skipped.

clang-tidy: pass.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

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[eugenis]

LGTM

compiler-rt/lib/scudo/standalone/primary32.h

if (UNLIKELY(!getRandom(reinterpret_cast<void *>(&Seed), sizeof(Seed))))
           static_cast<u32>(getMonotonicTime() ^
                            (reinterpret_cast<uptr>(SizeClassInfoArray) >> 6));
     const uptr PageSize = getPageSizeCached();
     for (uptr I = 0; I < NumClasses; I++) {
       SizeClassInfo *Sci = getSizeClassInfo(I);
       Sci->RandState = getRandomU32(&Seed);
       // See comment in the 64-bit primary about releasing smaller size classes.
       Sci->CanRelease = (ReleaseToOsInterval >= 0) &&
-                        (getSizeByClassId(I) >= (PageSize / 64));
+                        (I != SizeClassMap::BatchClassId) &&
+                        (getSizeByClassId(I) >= (PageSize / 32));
     }
     ReleaseToOsIntervalMs = ReleaseToOsInterval;
   }
   void init(s32 ReleaseToOsInterval) {
     memset(this, 0, sizeof(*this));
     initLinkerInitialized(ReleaseToOsInterval);
   }
 

compiler-rt/lib/scudo/standalone/primary64.h

for (uptr I = 0; I < NumClasses; I++) {
       // Releasing smaller size classes doesn't necessarily yield to a
       // meaningful RSS impact: there are more blocks per page, they are
       // randomized around, and thus pages are less likely to be entirely empty.
       // On top of this, attempting to release those require more iterations and
       // memory accesses which ends up being fairly costly. The current lower
       // limit is mostly arbitrary and based on empirical observations.
       // TODO(kostyak): make the lower limit a runtime option
       Region->CanRelease = (ReleaseToOsInterval >= 0) &&
-                           (getSizeByClassId(I) >= (PageSize / 64));
+                           (I != SizeClassMap::BatchClassId) &&
+                           (getSizeByClassId(I) >= (PageSize / 32));
       Region->RandState = getRandomU32(&Seed);
     }
     ReleaseToOsIntervalMs = ReleaseToOsInterval;
 
     if (SupportsMemoryTagging)
       UseMemoryTagging = systemSupportsMemoryTagging();
   }
   void init(s32 ReleaseToOsInterval) {