Add sk_calloc.  Remove SkMemory_stdlib, which seems unused.

I'm seeing basically no difference between malloc + bzero and calloc on my desktop, but on a Galaxy Nexus calloc is never slower, and significantly faster once the allocation size becomes large, both for allocation and for _reading_.

BUG=skia:1662
R=reed@google.com

Review URL: https://codereview.chromium.org/24251008

git-svn-id: http://skia.googlecode.com/svn/trunk@11414 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/MemoryTest.cpp b/tests/MemoryTest.cpp
new file mode 100644
index 0000000..4c3216b
--- /dev/null
+++ b/tests/MemoryTest.cpp
@@ -0,0 +1,12 @@
+#include "Test.h"
+#include "TestClassDef.h"
+
+DEF_TEST(memory_calloc, reporter) {
+    const size_t kNum = 200;
+    char* zeros = (char*)sk_calloc_throw(kNum*sizeof(char));
+
+    for (size_t i = 0; i < kNum; i++) {
+        REPORTER_ASSERT(reporter, 0 == zeros[i]);
+    }
+    sk_free(zeros);
+}