Add support for a custom built dynamic loader

[davidlt]

• Add PatchELF utility for patching ELF binaries in post-install
  step.
• Do ELF relocation for bin/$SCRAM_ARCH and test/$SCRAM_ARCH using
  CMS_INSTALL_PREFIX.
• Relocation is only done for slc6_amd64_* (current production
  architecture for CMSSW_7_2_X).

This makes IB/CMSSW_7_2_X/stable and IB/CMSSW_7_2_X/next identical.

Signed-off-by: David Abdurachmanov David.Abdurachmanov@cern.ch

[ktf]

This will not work on mac. Can you please add the relevant checks?

[smuzaffar]

@davidlt , can you put all the new
Requires: xxx

in %islinux?

[smuzaffar]

also please fix these:

• you do not need LDFLAGS in gcc-ccompiler.xml. Having it in gcc-cxxcompiler is enough.
• In cmssw-tool-conf.spec we have multiple Requires: glibc-toolfile (one within %islinux and one outside)

[davidlt]

Updated. That should do it.

[smuzaffar]

Looks much better now. Just a minor fix

• cmssw-tool-conf.spec: glibc-toolfile dependency is mentioned twice. Please clean it up and may be put it in %islinux %isamd64 (just to make it consistent with rest of the changes)

By the way what will happen if changeDynLoader is not set for a project? gcc-toolfile will set LDFLAGS=-Wl,-dynamic-linker,@GLIBC_ROOT@/lib64/ld.so , so if changeDynLoader is not set this mean there will be no relocation at install time .... right?

[davidlt]

Must be blind. Cleaned cmssw-tool-conf.spec.

You are correct changeDynLoader activates post-install relocation for SCRAM based project. We could replace changeDynLoader with some file in CMSDIST. We could read the content of this file (yes/no) in cmssw-tool-conf.spec, gcc-toolfile.spec, cmssw.spec and maybe coral.spec. This would complete allow to control it ON/OFF across multiple SPECs.