move SK_MMAP_SUPPORT into SkPreConfig, so we can know about its availability

trunk/src/core/SkData.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkData.h"
 #include "SkFlattenableBuffers.h"
 
+#if SK_MMAP_SUPPORT
+    #include <unistd.h>
+    #include <sys/mman.h>
+    #include <fcntl.h>
+    #include <errno.h>
+#endif
+
 SK_DEFINE_INST_COUNT(SkData)
 
 SkData::SkData(const void* ptr, size_t size, ReleaseProc proc, void* context) {
     fPtr = ptr;
     fSize = size;
     fReleaseProc = proc;
     fReleaseProcContext = context;
 }
 
 SkData::~SkData() {
@@ skipping 92 matching lines @@
     size_t size;
     if (NULL == cstr) {
         cstr = "";
         size = 1;
     } else {
         size = strlen(cstr) + 1;
     }
     return NewWithCopy(cstr, size);
 }
 
+#if SK_MMAP_SUPPORT
+static void sk_munmap_releaseproc(const void* addr, size_t length, void*) {
+    munmap(const_cast<void*>(addr), length);
+}
+
+SkData* SkData::NewFromMMap(const void* addr, size_t length) {
+    return SkNEW_ARGS(SkData, (addr, length, sk_munmap_releaseproc, NULL));
+}
+#else
+SkData* SkData::NewFromMMap(const void* addr, size_t length) {
+    return NULL;
+}
+#endif
+
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkData::flatten(SkFlattenableWriteBuffer& buffer) const {
     buffer.writeByteArray(fPtr, fSize);
 }
 
 SkData::SkData(SkFlattenableReadBuffer& buffer) {
     fSize = buffer.getArrayCount();
     fReleaseProcContext = NULL;
 
@@ skipping 160 matching lines @@
 }
 
 SkDataSet* SkDataSet::NewEmpty() {
     static SkDataSet* gEmptySet;
     if (NULL == gEmptySet) {
         gEmptySet = SkNEW_ARGS(SkDataSet, (NULL, 0));
     }
     gEmptySet->ref();
     return gEmptySet;
 }
+