Document new build commands in ReadMe

[nielx]

The ReadMe file is not yet updated to reflect the new package management style building.

The following instructions are still here, which (I think) is outdated.

Configure a GCC 2.95 Hybrid, from non-Haiku platform
----------------------------------------------------

  cd haiku-trunk/generated.x86gcc4
  ../configure --use-gcc-pipe --use-xattr \
    --build-cross-tools-gcc4 x86 ../../buildtools/ \
    --alternative-gcc-output-dir ../generated.x86gcc2
  cd ../generated.x86gcc2
  ../configure --use-gcc-pipe --use-xattr \
    --build-cross-tools ../../buildtools/ \
    --alternative-gcc-output-dir ../generated.x86gcc4

Configure a GCC 2.95 Hybrid, from within Haiku
----------------------------------------------

  cd haiku-trunk/generated.x86gcc4
  ../configure --use-gcc-pipe \
    --alternative-gcc-output-dir ../generated.x86gcc2 \
    --cross-tools-prefix /boot/develop/abi/x86/gcc4/tools/current/bin/
  cd ../generated.x86gcc2
  ../configure --use-gcc-pipe \
    --alternative-gcc-output-dir ../generated.x86gcc4 \
    --cross-tools-prefix /boot/develop/abi/x86/gcc2/tools/current/bin/

Additional information about GCC Hybrids can be found on the website,
http://www.haiku-os.org/guides/building/gcc-hybrid

[bonefish]

Updated the ReadMe in hrev46121. Will have a look at the documentation on the website in a second.

[bonefish]

IIRC I updated all outdated info in the website documentation that I encountered. Though I haven't read through everything. Please reopen/create a new ticket, if anything is still not up-to-date.

[diver]

​http://dev.haiku-os.org/wiki/PackageManagement/DirectoryStructure looks outdated.

[bonefish]

Yes, the whole PM documentation in the wiki hasn't been updated wrt the removal of /boot/common yet.