Makefile.am: Don't use -dynamic-too for .hpc_o files

It turns out that GHC 7.8's -dynamic-too is forbidden not only for
profiling builds object files, but also for those using HPC coverage.

This commit accordingly renames HFLAGS_NOPROF to HFLAGS_DYNAMIC
(since it now is not conditional on profiling any more),
and makes sure that it is not used for profiling or HPC.

This way we achieve that, for profiling+coverage builds
  - .dyn_o files are available for use in TH in the following 3 cases
  - .o files are for the normal binaries
  - .hpc_o files are for coverage-enabled test binaries
  - .prof_o files are for profiling binaries

We make .hpc_o files depend on the .o files because the creation of
the .o files will also create the .so files needed for TH.
This was already in place for .prof_o files.

This requires that HFLAGS now also contains `-itest/hs` since
the rule for .o files is now also responsible for building .o/.so files
in test/hs.

Signed-off-by: Niklas Hambuechen <niklash@google.com>