Remove empty newline in build.prop

Before:
cat build.prop

\# begin common build properties
\# autogenerated by build/make/tools/buildinfo_common.sh

After
cat build.prop
\# begin common build properties
\# autogenerated by build/make/tools/buildinfo_common.sh

Change-Id: I55a9cdc9a93e2d72ba4db97fef4c5e8c67421026
Test: m