fix gcj in gcc5

[howarth.at.macports@…]

The attached Portfile.diff, gcj-libiconv-linkage.patch and boehm-gc-darwin15-hack.patch corrects the build of gcj so that it is functional. The changes include...

1) Pass -with-libiconv-prefix=${prefix} to configure so that the proper libiconv is used (as the Portfile has depends_lib port:libiconv.

2) Reduce alignment in boehm-gc to 2 with boehm-gc-darwin15-hack.patch in order to suppress breakage from the recompilation of the system libunwind.dylib against Apple Clang 7.0 in darwin15.

3) Apply gcj-libiconv-linkage.patch to provide the appropriate linkage on libiconv automatically for executables created with gcj.

4) In order to create ecj1 during the build, ecj-4.9.jar is added to distfiles and copied into the source directory as ecj.jar per upstream's build instructions for gcj.

The functionality of the resulting gcj-mp-5 can be seen by compiling the testme.java source code....

public class testme { 
  public static void main(String args[]){ 
    System.out.println("Hello"); 
  } 
} 

using the command "gcj-mp-5 --main=testme -O testme.java" which will produce a functional a.out executable.

[howarth.at.macports@…]

patch to eliminate boehm-gc testsuite regressions against darwin15's system unwinder

[howarth.at.macports@…]

patch to provide missing linkage for libiconv on the gcj spec file