Run Lintian after built package is copied to $SRC_PATH

Because of `set -e`, if there are any warnings, then the package won't be
copied back to the source directory. For now, there are definitely going to
remain some Lintian warnings which we'll want to ignore.
Also updates comments to make them more descriptive.

zcutil/build-debian-package.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 ## Usage:
-##  ./build_DEBIAN_package.sh
+##  ./zcutil/build-debian-package.sh
 
 set -e
 set -x
@@ -29,9 +29,9 @@ DEB_MAN=$BUILD_DIR/usr/share/man/man1
 mkdir -p $BUILD_DIR/DEBIAN $DEB_BIN $DEB_DOC $DEB_MAN
 chmod 0755 -R $BUILD_DIR/*
 
-# Copy control
+# Copy control file
 cp $SRC_DEB/control $BUILD_DIR/DEBIAN
-# Currently empty
+# Package maintainer scripts (currently empty)
 #cp $SRC_DEB/postinst $BUILD_DIR/DEBIAN
 #cp $SRC_DEB/postrm $BUILD_DIR/DEBIAN
 #cp $SRC_DEB/preinst $BUILD_DIR/DEBIAN
@@ -55,9 +55,9 @@ gzip --best -n $DEB_DOC/changelog.Debian
 gzip --best -n $DEB_MAN/zcashd.1
 gzip --best -n $DEB_MAN/zcash-cli.1
 
-# Create the deb package
+# Create the Debian package
 fakeroot dpkg-deb --build $BUILD_DIR
-lintian -i $BUILD_PATH/$PACKAGE_NAME-$PACKAGE_VERSION-amd64.deb
 cp $BUILD_PATH/$PACKAGE_NAME-$PACKAGE_VERSION-amd64.deb $SRC_PATH
-
+# Analyze with Lintian, reporting bugs and policy violations
+lintian -i $SRC_PATH/$PACKAGE_NAME-$PACKAGE_VERSION-amd64.deb
 exit 0