gluegen: directly use git subcommands rather than sed over a temp file

git symbolic-ref is the preferred way (as of 1.7.10) to parse the current branch
name.  This even works for the detached head case.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>

make/build.xml

@@ -66,27 +66,33 @@
 
     <property name="gluegen.build.number" value="manual"/>
     <property name="gluegen.build.id"     value="${version.timestamp}"/>
-    <mkdir dir="${build}" />
-    <exec dir="." executable="git" logError="true" failonerror="false" failifexecutionfails="false"
-              output="${build}/localbranch.raw">
-        <arg line="branch --no-color"/>
-    </exec>
-    <exec dir="." executable="sed" logError="true" failonerror="false" failifexecutionfails="false"
-              outputproperty="gluegen.build.branch">
-        <arg line="-e '/^[^*]/d' -e 's/* \(.*\)/\1/' '${build}/localbranch.raw'"/>
+
+    <exec dir="${project.root}" executable="git" logError="false" failonerror="false" failifexecutionfails="false"
+          outputproperty="gluegen.build.branch.raw" resultproperty="gluegen.build.branch.ret">
+          <arg value="symbolic-ref"/>
+          <arg value="-q"/>
+          <arg value="--short"/>
+          <arg value="HEAD"/>
     </exec>
-    <property name="gluegen.build.branch" value="manual"/> <!-- fallback -->
-    <exec dir="${project.root}" executable="git" logError="true" failonerror="false" failifexecutionfails="false"
-              outputproperty="gluegen.build.commit">
-        <arg line="rev-parse HEAD"/>
+    <condition property="gluegen.build.branch" value="${gluegen.build.branch.raw}" else="manual">
+      <not> <isfailure code="${gluegen.build.branch.ret}"/> </not>
+    </condition>
+
+    <exec dir="${project.root}" executable="git" logError="false" failonerror="false" failifexecutionfails="false"
+          outputproperty="gluegen.build.commit.raw" resultproperty="gluegen.build.commit.ret">
+          <arg value="rev-parse"/>
+          <arg value="HEAD"/>
     </exec>
-    <property name="gluegen.build.commit" value="manual"/> <!-- fallback -->
+    <condition property="gluegen.build.commit" value="${gluegen.build.commit.raw}" else="manual">
+      <not> <isfailure code="${gluegen.build.commit.ret}"/> </not>
+    </condition>
 
     <property name="gluegen.version" value="${jogamp.version.base}-b${gluegen.build.number}-${version.timestamp}" />
 
     <property name="stub.includes.dir" value="stub_includes" /> <!-- NOTE:  this MUST be relative for FileSet -->
 
     <!-- The generated source directories. -->
+    <mkdir dir="${build}" />
     <property name="src.generated"          value="${build}/gensrc" />
     <property name="src.generated.java"     value="${src.generated}/java" />
     <property name="src.generated.c"        value="${src.generated}/native" />