[MNG-5829] mvn shell script fails with syntax error on Solaris 10

Use backticks instead of $(..) for the scripting added in MNG-5767.
Solaris's /bin/sh isn't POSIX-compliant enough to recognise the first
form.

This closes #50.

apache-maven/src/bin/mvn

@@ -192,14 +192,14 @@ fi
 find_maven_basedir() {
   local basedir
   local wdir
-  basedir="$(pwd)"
-  wdir="$(pwd)"
+  basedir="`pwd`"
+  wdir="`pwd`"
   while [ "$wdir" != '/' ] ; do
     if [ -d "$wdir"/.mvn ] ; then
       basedir=$wdir
       break
     fi
-    wdir="$(cd "$wdir/.."; pwd)"
+    wdir="`cd "$wdir/.."; pwd`"
   done
   echo "${basedir}"
 }
@@ -207,12 +207,12 @@ find_maven_basedir() {
 # concatenates all lines of a file
 concat_lines() {
   if [ -f "$1" ]; then
-    echo "$(tr -s '\n' ' ' < "$1")"
+    echo "`tr -s '\n' ' ' < "$1"`"
   fi
 }
 
-MAVEN_PROJECTBASEDIR="${MAVEN_BASEDIR:-$(find_maven_basedir)}"
-MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+MAVEN_PROJECTBASEDIR="${MAVEN_BASEDIR:-`find_maven_basedir`}"
+MAVEN_OPTS="`concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config"` $MAVEN_OPTS"
 
 # For Cygwin, switch project base directory path to Windows format before
 # executing Maven otherwise this will cause Maven not to consider it.

apache-maven/src/bin/mvnDebug

@@ -31,4 +31,4 @@ MAVEN_DEBUG_OPTS="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,addre
 
 echo Preparing to execute Maven in debug mode
 
-env MAVEN_OPTS="$MAVEN_OPTS" MAVEN_DEBUG_OPTS="$MAVEN_DEBUG_OPTS" "$(dirname "$0")/mvn" "$@"
+env MAVEN_OPTS="$MAVEN_OPTS" MAVEN_DEBUG_OPTS="$MAVEN_DEBUG_OPTS" "`dirname "$0"`/mvn" "$@"

apache-maven/src/bin/mvnyjp

@@ -32,4 +32,4 @@ if [ ! -f "$YJPLIB" ]; then
   exit 1
 fi
 
-env MAVEN_OPTS="-agentpath:$YJPLIB=onexit=snapshot,onexit=memory,tracing,onlylocal $MAVEN_OPTS" "$(dirname "$0")/mvn" "$@"
+env MAVEN_OPTS="-agentpath:$YJPLIB=onexit=snapshot,onexit=memory,tracing,onlylocal $MAVEN_OPTS" "`dirname "$0"`/mvn" "$@"