Fixed redefinition of 'i' with a different type error

Renamed the redefinition of 'i' to 'k'.

Change-Id: I8ae8ed1dee42c896fa15e55be8d58b33b29254f4
Author: Tareq A. Siraj <tareq.a.siraj@intel.com>
Reviewed-by: Kevin P Schoedel <kevin.p.schoedel@intel.com>
diff --git a/media/libstagefright/matroska/MatroskaExtractor.cpp b/media/libstagefright/matroska/MatroskaExtractor.cpp
index feb8e40..8f7d12b 100644
--- a/media/libstagefright/matroska/MatroskaExtractor.cpp
+++ b/media/libstagefright/matroska/MatroskaExtractor.cpp
@@ -902,8 +902,8 @@
                 ++j;
 
                 size_t blockSize = 0;
-                for (int i = 0; i < iter.block()->GetFrameCount(); ++i) {
-                    blockSize += iter.block()->GetFrame(i).len;
+                for (int k = 0; k < iter.block()->GetFrameCount(); ++k) {
+                    blockSize += iter.block()->GetFrame(k).len;
                 }
 
                 if (blockSize > maxBlockSize) {