MAP_NORESERVE was never implemented in FreeBSD as has been retired

as of https://reviews.freebsd.org/D848. This makes V8 build on
FreeBSD-current (and the forthcoming 11).

BUG=none
LOG=n

Review URL: https://codereview.chromium.org/1025823003

Cr-Commit-Position: refs/heads/master@{#27348}

src/base/platform/platform-freebsd.cc

@@ -188,7 +188,7 @@ VirtualMemory::VirtualMemory(size_t size, size_t alignment)
   void* reservation = mmap(OS::GetRandomMmapAddr(),
                            request_size,
                            PROT_NONE,
-                           MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
+                           MAP_PRIVATE | MAP_ANON,
                            kMmapFd,
                            kMmapFdOffset);
   if (reservation == MAP_FAILED) return;
@@ -260,7 +260,7 @@ void* VirtualMemory::ReserveRegion(size_t size) {
   void* result = mmap(OS::GetRandomMmapAddr(),
                       size,
                       PROT_NONE,
-                      MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
+                      MAP_PRIVATE | MAP_ANON,
                       kMmapFd,
                       kMmapFdOffset);
 
@@ -288,7 +288,7 @@ bool VirtualMemory::UncommitRegion(void* base, size_t size) {
   return mmap(base,
               size,
               PROT_NONE,
-              MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | MAP_FIXED,
+              MAP_PRIVATE | MAP_ANON | MAP_FIXED,
               kMmapFd,
               kMmapFdOffset) != MAP_FAILED;
 }