Solaris/OpenBSD/FreeBSD: [heap] Uncommit unused large object page memory.

src/base/platform/platform-openbsd.cc

Index: src/base/platform/platform-openbsd.cc
diff --git a/src/base/platform/platform-openbsd.cc b/src/base/platform/platform-openbsd.cc
index 6ecf1f12ba7286b2d1bd3a3ab7644c3c73a043f8..29c518a898767f14d8477f233e857f81bc63e0c7 100644
--- a/src/base/platform/platform-openbsd.cc
+++ b/src/base/platform/platform-openbsd.cc
@@ -277,6 +277,10 @@ bool VirtualMemory::UncommitRegion(void* base, size_t size) {
               kMmapFdOffset) != MAP_FAILED;
 }
 
+bool VirtualMemory::ReleasePartialRegion(void* base, size_t size,
+                                         void* free_start, size_t free_size) {
+  return munmap(free_start, free_size) == 0;
+}
 
 bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
   return munmap(base, size) == 0;