Fix Java detection on some Linux distributions

On some Linux distributions (spotted here on OpenMandriva Lx, but I'm
pretty sure some others do the same thing), "which javac" returns
/usr/bin/javac, which is a symlink to "../../etc/alternatives/javac",
which in turn points at whatever the JDK the user picked as his default.

Given "../../etc/alternatives/javac" is a relative symlink, the next
iteration of LSLINE=$(ls -l "$JAVAC") fails (no ../../etc/alternatives/java
relative to the build directory), causing tools.jar not to be found.

Using realpath and readlink where possible should work in all cases.

Change-Id: Ic60ac84a5b263dc1c1f2960092a7549d1024ed2e
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
diff --git a/core/find-jdk-tools-jar.sh b/core/find-jdk-tools-jar.sh
index f150a9a..0224829 100755
--- a/core/find-jdk-tools-jar.sh
+++ b/core/find-jdk-tools-jar.sh
@@ -2,7 +2,13 @@
 if [ "x$ANDROID_JAVA_HOME" != x ] && [ -e "$ANDROID_JAVA_HOME/lib/tools.jar" ] ; then
     echo $ANDROID_JAVA_HOME/lib/tools.jar
 else
-    JAVAC=$(which javac)
+    JAVAC=$(realpath $(which javac) 2>/dev/null)
+    if [ -z "$JAVAC" ]; then
+        JAVAC=$(readlink -f $(which javac) 2>/dev/null)
+    fi
+    if [ -z "$JAVAC" ]; then
+        JAVAC=$(which javac)
+    fi
     if [ -z "$JAVAC" ] ; then
         exit 1
     fi