package.cmd: don't exit parent when displaying usage

Author: jef-n

ms-windows/osgeo4w/package-nightly.cmd

@@ -319,7 +319,7 @@ goto end
 :usage
 echo usage: %0 version package packagename arch [sha [site]]
 echo sample: %0 2.11.0 38 qgis-dev x86_64 339dbf1 qgis.org
-exit
+exit /b 1
 
 :error
 echo BUILD ERROR %ERRORLEVEL%: %DATE% %TIME%

ms-windows/osgeo4w/package.cmd

@@ -465,7 +465,7 @@ goto end
 :usage
 echo usage: %0 version package packagename arch [sha [site]]
 echo sample: %0 2.0.1 3 qgis x86 f802808
-exit
+exit /b 1
 
 :error
 echo BUILD ERROR %ERRORLEVEL%: %DATE% %TIME%