VC 2010 Compile Issues

[cfis]

These changes allow VC++ to compile ruby-debug-bas19x.

Changes are:

• In extconf.rb, iseq.h requires vm_core.h to compile. Not sure why this doesn't blow up other compilers
• The declarations for rb_vm_get_sourceline and rb_iseq_compile_with_option do not match the ones in vm_core.h. They include an extra RUBY_EXTERN and therefore are not correct (note for VC RUBY_EXTERN is defined as declspec(dllimport) when compiling against a dll.
• The remaining changes are due to VC++ requiring variable to be defined at the start of blocks when compiling c code.

Note this fixes the compilation issues, but there is still a linker issue that is due to Ruby. See http://redmine.ruby-lang.org/issues/5193

Thanks - Charlie

[denofevil]

Works ok on rvm-based 1.9.2 also, merged

[cfis]

Thanks - I'll also give it a spin on MinGW.

Charlie