ITS#8169 Allow passing mandir to make install

The motivation for this change is my distribution moving to a multiarch
layout. While the architecture specific stuff (binaries, libraries,
etc.) is installed under /usr/${host}/{bin,lib,...} architecture-independent
data should still be installed to /usr/share/.

libraries/liblmdb/Makefile

@@ -27,6 +27,7 @@ CFLAGS	= $(THREADS) $(OPT) $(W) $(XCFLAGS)
 LDLIBS	=
 SOLIBS	=
 prefix	= /usr/local
+mandir = $(prefix)/man
 
 ########################################################################
 
@@ -45,7 +46,7 @@ install: $(ILIBS) $(IPROGS) $(IHDRS)
 	for f in $(IPROGS); do cp $$f $(DESTDIR)$(prefix)/bin; done
 	for f in $(ILIBS); do cp $$f $(DESTDIR)$(prefix)/lib; done
 	for f in $(IHDRS); do cp $$f $(DESTDIR)$(prefix)/include; done
-	for f in $(IDOCS); do cp $$f $(DESTDIR)$(prefix)/man/man1; done
+	for f in $(IDOCS); do cp $$f $(DESTDIR)$(mandir)/man1; done
 
 clean:
 	rm -rf $(PROGS) *.[ao] *.[ls]o *~ testdb