Install fixes, $prefix supported better, strip binaries and .so files

- Makefile fixes for installation, paths encoded wrong
- Strip binaries + .so files, support for $(CROSS) toolchain strip
- Default install is now to /sbin/finit and /usr/
- Use the 'plugindir' environemnt variable instead of 'PLUGIN_DIR'

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

common.mk

@@ -1,7 +1,9 @@
 # Some junk files we always want to be removed when doing a make clean.
 JUNK       = *~ *.bak *.aux *.dvi *.idx *.ind *.log *.ps *.map .*.d DEADJOE semantic.cache *.gdb *.elf core core.*
 MAKE      := @$(MAKE)
-MAKEFLAGS  = --no-print-directory
+MAKEFLAGS  = --no-print-directory --silent
+INSTALL   := install -b
+STRIPINST := $(INSTALL) -s --strip-program=$(CROSS)strip -m 0755
 
 # Smart autodependecy generation via GCC -M.
 .%.d: %.c