fix problem with GSP class name

The problem comes up in a multi project build if one of the subproject names has a hyphen in it (cache-gemfire, as an example).  "cache-gemfire" ends up being part of the generated GSP class name which is invalid.

grails-gsp/src/main/groovy/org/grails/gsp/compiler/GroovyPageCompiler.groovy

@@ -97,7 +97,8 @@ class GroovyPageCompiler {
             packageDir += generateJavaName(relPackagePath)
         }
 
-        def className = packageDir.replace('/','_')
+        def className = generateJavaName(packageDir.replace('/','_'))
+
         className += generateJavaName(gspfile.name)
         // using default package because of GRAILS-5022
         packageDir = ''