* configure.ac: disable using __builtin_setjmp to avoid errors when execution
  globally jumps out of JITted code. Specify -std=gnu99 to JIT compilation
  to avoid errors regarding the "restrict" keyword in the precompiled header.
  Specify -shared in addition to -Wl,-G when building shared libraries
  to make mjit_build_dir.so expose the MJIT_BUILD_DIR symbol.  Use LDR_PRELOAD
  to load mjit_build_dir.so.

* mjit_worker.c: do not specify -nodefaultlibs or -nostdlibs because on AIX
  JITted code internally refers to the memcpy function.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66202 b2dd03c8-39d4-4d8f-98ff-823fe69b080e