[uClibc] ldconfig troubles (but comes with fixes!)

[Mike Frysinger]

while playing around with Gentoo on uClibc, i hit some troubles with ldconfig

first, i found that it kept trying to read 'etc/ld.so.conf' ... it didnt want 
to read '/etc/ld.so.conf' ... looking at the source, the default conf file is 
defined as UCLIBC_RUNTIME_PREFIX "etc/ld.so.conf" ... all fine and dandy, but 
the utils/Makefile builds the .c files with this:
-DUCLIBC_RUNTIME_PREFIX=$(R_PREFIX)
i couldnt find where R_PREFIX was defined/used anywhere else, but i did find 
that every other time UCLIBC_RUNTIME_PREFIX was defined, it was set like:
-DUCLIBC_RUNTIME_PREFIX=\"$(RUNTIME_PREFIX)\"
changing the utils/Makefile to be like this fixed things for me

next up, i found that i wasnt getting an /etc/ld.so.cache file when i ran 
`ldconfig` ... looking at the code, USE_CACHE needs to be defined ... 
Rules.mak has a line that reads LIBRARY_CACHE:=#-DUSE_CACHE by default, but 
then LIBRARY_CACHE is never used anywhere :)
so the fix here is to add $(LIBRARY_CACHE) to the lines in utils/Makefile 
where the .c files are compiled

perhaps a suggestion then ?  in my mind it makes sense to utilize a cache file 
when running uclibc native but perhaps not while cross compiling ... so 
perhaps add LIBRARY_CACHE:=-DUSE_CACHE to the section in Rules.mak where LDSO 
is set to the uclibc linker (i.e. native) but set LIBRARY_CACHE:=#-DUSE_CACHE 
where LDSO is the $(SYSTEM_LDSO) (i.e. cross compiling)
-mike