Fixed Chart.build.xml

[pcanelas]

Hi,

When trying to run defects4j on Chart 1, it raised the following error:

compile:
    [mkdir] Created dir: /tmp/Chart_2/build
    [javac] /defects4j/framework/projects/Chart/Chart.build.xml:57: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 654 source files to /tmp/Chart_2/build
    [javac] warning: [options] bootstrap class path not set in conjunction with -source 6
    [javac] warning: [options] source value 6 is obsolete and will be removed in a future release
    [javac] warning: [options] target value 1.6 is obsolete and will be removed in a future release
    [javac] warning: [options] To suppress warnings about obsolete options, use -Xlint:-options.
    [javac] /tmp/Chart_2/source/org/jfree/chart/axis/Axis.java:1152: error: unmappable character (0xC2) for encoding US-ASCII
    [javac]             return;  // no need to create entity if we can??t save it anyways...
    [javac]                                                           ^
    [javac] /tmp/Chart_2/source/org/jfree/chart/axis/Axis.java:1152: error: unmappable character (0xB4) for encoding US-ASCII
    [javac]             return;  // no need to create entity if we can??t save it anyways...
    [javac]                                                            ^
    [javac] 2 errors
    [javac] 4 warnings

BUILD FAILED
/defects4j/framework/projects/Chart/Chart.build.xml:57: Compile failed; see the compiler error output for details.

Adding encoding="UTF-8" to the compilation should address the issue.