on x86_64, install libs to /usr/lib64 if /usr/lib is inexistent. bug reported by Anton Bolshakov
diff --git a/Makefile b/Makefile
index 825e561..75b02ed 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,13 @@
 PREFIX ?= /usr
 DESTDIR ?=
 INCDIR = $(DESTDIR)$(PREFIX)/include
+
 LIBDIR = $(DESTDIR)$(PREFIX)/lib
+# on x86_64, we might have /usr/lib64 directory instead of /usr/lib
+MACHINE := $(shell uname -m)
+ifeq ($(MACHINE), x86_64)
+if [ ! -d “$(LIBDIR)" ]; then LIBDIR = $(DESTDIR)$(PREFIX)/lib64;  fi
+endif
 
 INSTALL_DATA ?= install -m0644
 INSTALL_LIBRARY ?= install -m0755