SCM_INTERNAL causes problems

[Patrick Horgan <phorgan1@gmail.com>]

When building lilypond the following variables:
`scm_i_gc_admin_mutex'          SCM_INTERNAL gc.h
`scm_i_init_mutex'              SCM_INTERNAL init.h
`scm_i_locale_mutex'            SCM_INTERNAL posix.h
`scm_i_misc_mutex'              SCM_INTERNAL threads.h
`scm_i_port_table_mutex'        SCM_INTERNAL ports.h
`scm_i_port_table_room'         SCM_INTERNAL ports.h
`scm_i_port_weak_hash'          SCM_INTERNAL ports.h
`scm_i_signal_delivery_thread'  SCM_INTERNAL scmsigs.h
`scm_i_structs_to_free'         SCM_INTERNAL struct.h
`scm_i_sweep_mutex'             SCM_INTERNAL gc.h

show up as multiple defines in the link phase and keep lilypond from 
building.  The problem is that the include files they are in are 
included in different .c files, so the variable definitions are in 
various .o files.  If they are really supposed to just have internal 
visibility in guile libraries wouldn't it be better to not put them in 
include files that are installed as part of make install?  I mean, you 
could put #ifdefs around them so that they wouldn't show up in builds of 
other programs like lilypond, but it seems a cleaner solution to put 
them in private include files that are never installed publicly, but 
only used in the build.

Patrick