Reserve enough space for RTSP CSD

make parameters to GetSizeWidth() reflect values being used in
corresponding EncodeSize() invocations so we won't overflow the buffer.

Bug: 123701862
Test: y
Change-Id: I78596176e6042c95582494a8ae1b9c3160bf5955
diff --git a/media/libstagefright/rtsp/APacketSource.cpp b/media/libstagefright/rtsp/APacketSource.cpp
index cfafaa7..a7545ad 100644
--- a/media/libstagefright/rtsp/APacketSource.cpp
+++ b/media/libstagefright/rtsp/APacketSource.cpp
@@ -377,8 +377,8 @@
     ALOGI("VOL dimensions = %dx%d", *width, *height);
 
     size_t len1 = config->size() + GetSizeWidth(config->size()) + 1;
-    size_t len2 = len1 + GetSizeWidth(len1) + 1 + 13;
-    size_t len3 = len2 + GetSizeWidth(len2) + 1 + 3;
+    size_t len2 = len1 + GetSizeWidth(len1 + 13) + 1 + 13;
+    size_t len3 = len2 + GetSizeWidth(len2 + 3) + 1 + 3;
 
     sp<ABuffer> csd = new ABuffer(len3);
     uint8_t *dst = csd->data();