RFR JDK-8240241: Add support for JCov DiffCoverage to make files

[Alexandre (Shura) Iline]

Hi.

Can you take a look on this change introducing make support for JCov DiffCoverage command.

DiffCoverage allows to generate a textual report showing coverage for only changed source code,

This is an example of how the functionality can be used:
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$ make  jcov-test TEST=open/test/langtools/jdk/javadoc/doclet TEST_OPTS_JCOV_DIFF_CHANGESET=58193
$ cat build/linux-x64/test-results/jcov-output/diff_coverage_report
   jdk/javadoc/internal/doclets/formats/html/markup/HtmlStyle.java: HtmlStyle.void <clinit>()
+    106 |    notes,
   jdk/javadoc/internal/doclets/formats/html/SerializedFormWriterImpl.java: SerializedFormWriterImpl.jdk.javadoc.internal.doclets.toolkit.Content getSerialUIDInfoHeader()
+    187 |        return new HtmlTree(HtmlTag.DL).setStyle(HtmlStyle.nameValue);
   jdk/javadoc/internal/doclets/formats/html/HtmlDocletWriter.java: HtmlDocletWriter.void <init>(jdk.javadoc.internal.doclets.formats.html.HtmlConfiguration,jdk.javadoc.internal.d
oclets.toolkit.util.DocPath)
     345 |     * @param htmlTree the documentation tree to which the tags will be added
     347 |    protected void addTagsInfo(Element e, Content htmlTree) {
+    351 |        Content dl = new HtmlTree(HtmlTag.DL).setStyle(HtmlStyle.notes);
+    360 |        htmlTree.add(dl);
   jdk/javadoc/internal/doclets/formats/html/HtmlSerialFieldWriter.java: HtmlSerialFieldWriter.void addMemberTags(javax.lang.model.element.VariableElement,jdk.javadoc.internal.doc
lets.toolkit.Content)
+    203 |        Content dlTags = new HtmlTree(HtmlTag.DL).setStyle(HtmlStyle.notes);
   jdk/javadoc/internal/doclets/formats/html/ClassWriterImpl.java: ClassWriterImpl.void addParamInfo(jdk.javadoc.internal.doclets.toolkit.Content)
+    354 |                classInfoTree.add(HtmlTree.DL(paramInfo).setStyle(HtmlStyle.notes));
   jdk/javadoc/internal/doclets/formats/html/HtmlSerialMethodWriter.java: HtmlSerialMethodWriter.void addMemberTags(javax.lang.model.element.ExecutableElement,jdk.javadoc.internal
.doclets.toolkit.Content)
+    162 |        Content dlTags = new HtmlTree(HtmlTag.DL).setStyle(HtmlStyle.notes);
...
lines: 428 new; 40 covered; 4 not covered; 43 not code; 341 no information
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Webrev: http://cr.openjdk.java.net/~shurailine/JDK-8240241/webrev.00/

Shura.