Move libmemunreachable into namespace android

Putting libmemunreachable in the global C++ namespace was an oversight,
move it into namespace android.

Test: m -j checkbuild
Change-Id: I0799906f6463178cb04a719bb4054cad33a50dbe
diff --git a/libmemunreachable/LineBuffer.cpp b/libmemunreachable/LineBuffer.cpp
index 0709fdd..4ea0542 100644
--- a/libmemunreachable/LineBuffer.cpp
+++ b/libmemunreachable/LineBuffer.cpp
@@ -23,6 +23,8 @@
 
 #include "LineBuffer.h"
 
+namespace android {
+
 LineBuffer::LineBuffer(int fd, char* buffer, size_t buffer_len)
     : fd_(fd), buffer_(buffer), buffer_len_(buffer_len) {}
 
@@ -60,3 +62,5 @@
     bytes_ += bytes;
   }
 }
+
+}  // namespace android