changes for detecting and building for clang/binutils elf

and minor fixes:
 . add ack/clean target to lib, 'unify' clean target
 . add includes as library dependency
 . mk: exclude warning options clang doesn't have in non-gcc
 . set -e in lib/*.sh build files
 . clang compile error circumvention (disable NOASSERTS for release builds)

commands/unstack/unstack.sh

@@ -34,13 +34,11 @@ then	GNM=gnm
 else	GNM=nm
 fi
 
-ELFNM=/usr/gnu_cross/bin/i386-pc-minix3-nm
-
 # Invoke gnu nm or ack nm?
 if file $executable | grep NSYM >/dev/null 2>&1
 then	NM="$GNM --radix=d"
 elif file $executable | grep ELF >/dev/null 2>&1
-then	NM="$ELFNM --radix=d"
+then	NM="$GNM --radix=d"
 else	NM="acknm -d"
 fi