hg: panama/dev: 8215570: jextract should warn when no output is emitted

[maurizio.cimadamore at oracle.com]

Changeset: 1fab94e8324e
Author:    mcimadamore
Date:      2018-12-19 16:27 +0000
URL:       http://hg.openjdk.java.net/panama/dev/rev/1fab94e8324e

8215570: jextract should warn when no output is emitted
Reviewed-by: hjen

! src/jdk.jextract/share/classes/com/sun/tools/jextract/Main.java
! src/jdk.jextract/share/classes/com/sun/tools/jextract/Writer.java
! src/jdk.jextract/share/classes/com/sun/tools/jextract/resources/Messages.properties
+ test/jdk/com/sun/tools/jextract/missing/NoOutputTest.java
+ test/jdk/com/sun/tools/jextract/missing/allmissing.h