Running Linux Slackware 13.37

DUMB INSTALLATION had multiple errors, most along the lines of:

gcc -Iinclude -Wall -W -Wwrite-strings -Wstrict-prototypes -Wmissing-declarations -DDUMB_DECLARE_DEPRECATED -O2 -ffast-math -fomit-frame-pointer -c -o obj/unix/release/itread.o src/it/itread.c
src/it/itread.c: In function 'it_read_old_instrument':
src/it/itread.c:324:2: warning: pointer targets in passing argument 1 of 'dumbfile_getnc' differ in signedness
include/dumb.h:183:6: note: expected 'char *' but argument is of type 'unsigned char *'

I'd post a link the the Linux Questions Forum (but it said something about URL's not being shown when I registered for here, if you want you can go to page 2 of Linux Questions/Software
post "gcc libraries (Allegro and dependencies)"

PHYSFS INSTALLATION error:

sys/ucred.h - not found

ALLEGRO INSTALLATION errors:

Looking for include files ALLEGRO_HAVE_MACHINE_SOUNDCARD_H - not found.
Looking for include files ALLEGRO_HAVE_OSATOMIC_H - not found.
Looking for getexecname - not found

Performing Test ALLEGRO_HAVE_PROCFS_ARGCV - Failed
Performing Test ALLEGRO_HAVE_SV_PROCFS_H - Failed
Looking for pthread_create in pthreads - not found
Looking for X11/extensions/xf86vmode.h - not found
checking for module 'libpulse-simple'
-- package 'libpulse-simple' not found
Could NOT find OpenAL (missing: OPENAL_LIBRARY OPENAL_INCLUDE_DIR)
Could NOT find DUMB (missing: DUMB_INCLUDE_DIR DUMB_LIBRARY)
WARNING: libdumb not found or compile test failed, disabling support. <http://dumb.sourceforge.net/>

gcc says it can't find Allegro.h, however after ages of searching I found the Allegro files (I've no idea where Linux installs programs).

So how do I get gcc to know where Allgro library is? (assuming everything has been installed correctly).

UPDATE on Physfs error:

Nope: some BSD Unix systems have that header, but Linux doesn't. That
message is saying we noticed this, and presumably did the right thing.

We use that header for CD-ROM detection...Linux does the same thing in a
different way.

--ryan. (I emailed this guy who manages Physfs webpage & that is his reply)

Thats great.

I'm quite disappointed that this wasn't mentioned in the installation instructions, as it seems to be a vital step as part of a 'complete installation'.

Once I uncompressed Allegro there were several files on how to install Allegro on different systems.
I only vaguely recall them, as I focused on the unix like(Linux) installation instructions, and I don't recall it saying anything else, or pointing me to any other instruction files. (I could extract the files and read these things again and post my findings, if you'd like a view from an inexperienced Linux user).

Yes, 'sudo ldconfig' should definitely be added.
Perhaps it is an obvious final step to regular linux users.