Replace FOURC('a', 'b', 'c', 'd') with FOURCC("abcd")

Test: compare disassembly before/after

Change-Id: I8f9c75d19f2dcd0f0f31a082c0e98cd7eb6655a4
diff --git a/media/extractors/mp4/SampleTable.cpp b/media/extractors/mp4/SampleTable.cpp
index d242798..7db984a 100644
--- a/media/extractors/mp4/SampleTable.cpp
+++ b/media/extractors/mp4/SampleTable.cpp
@@ -37,13 +37,13 @@
 namespace android {
 
 // static
-const uint32_t SampleTable::kChunkOffsetType32 = FOURCC('s', 't', 'c', 'o');
+const uint32_t SampleTable::kChunkOffsetType32 = FOURCC("stco");
 // static
-const uint32_t SampleTable::kChunkOffsetType64 = FOURCC('c', 'o', '6', '4');
+const uint32_t SampleTable::kChunkOffsetType64 = FOURCC("co64");
 // static
-const uint32_t SampleTable::kSampleSizeType32 = FOURCC('s', 't', 's', 'z');
+const uint32_t SampleTable::kSampleSizeType32 = FOURCC("stsz");
 // static
-const uint32_t SampleTable::kSampleSizeTypeCompact = FOURCC('s', 't', 'z', '2');
+const uint32_t SampleTable::kSampleSizeTypeCompact = FOURCC("stz2");
 
 ////////////////////////////////////////////////////////////////////////////////