[m-rev.] for review: bump the minimum version of Java required

[Julien Fischer]

Does anyone have any objections to the following?
(The change itself is trivial and doesn't require a review.)

----------------------------

Bump the minimum version of Java required.

NEWS:
README.Java:
     Require at least Java SE 8 or equivalent.

m4/mercury.m4:
     Check for at least the above version of Java.

Julien

diff --git a/NEWS b/NEWS
index 43c00d7..9e1316f 100644
--- a/NEWS
+++ b/NEWS
@@ -96,7 +96,7 @@ Changes that may break compatibility:
    replaced with `oa' and `ia' respectively.

  * The minimum version of the Java platform required by Mercury's Java
-  backend is now Java SE 6.
+  backend is now Java SE 8.

  * The representation of integer constants in the standard library's term and
    lexer modules has been generalised.  The base, signedness and size of each
diff --git a/README.Java b/README.Java
index c129c12..9eb5bd4 100644
--- a/README.Java
+++ b/README.Java
@@ -7,7 +7,7 @@ Java bytecode suitable for running the Java SE runtime system.  The port is
  mostly complete, but some parts of the Mercury standard library are not yet
  implemented (for a full list see the FAQ below).

-The port requires Java SE 6 or higher -- older versions of Java are *not*
+The port requires Java SE 8 or higher -- older versions of Java are *not*
  supported.

  PREREQUISITES
diff --git a/m4/mercury.m4 b/m4/mercury.m4
index a81f645..7e6cbc2 100644
--- a/m4/mercury.m4
+++ b/m4/mercury.m4
@@ -492,7 +492,7 @@ if test "$JAVAC" != "" -a "$JAVA_INTERPRETER" != "" -a "$JAR" != ""; then
  	cat > conftest.java << EOF
  		// This program simply retrieves the constant
  		// specifying the version number of the Java SDK and
-		// checks it is at least 1.6, printing "Hello, world"
+		// checks it is at least 1.8, printing "Hello, world"
  		// if successful.
  		public class conftest {
  		    public static void main (String[[]] args) {
@@ -512,7 +512,7 @@ if test "$JAVAC" != "" -a "$JAVA_INTERPRETER" != "" -a "$JAR" != ""; then
  				version = 0f;
  			}

-			if (version >= 1.6) {
+			if (version >= 1.8) {
  				System.out.println("Hello, world\n");
  			} else {
  				System.out.println("Nope, sorry.\n");