Fix install_name and versioning on OSX.

src/Makefile

@@ -199,7 +199,8 @@ TARGET_AR= $(CROSS)ar rcus
 TARGET_STRIP= $(CROSS)strip
 
 TARGET_SONAME= libluajit-$(ABIVER).so.$(MAJVER)
-TARGET_DYLIBNAME= libluajit-$(NODOTABIVER).$(MAJVER).$(MINVER).$(RELVER).dylib
+TARGET_DYLIBNAME= libluajit-$(NODOTABIVER).$(MAJVER).dylib
+TARGET_DYLIBPATH= $(or $(PREFIX),/usr/local)/lib/$(TARGET_DYLIBNAME)
 TARGET_DLLNAME= lua$(NODOTABIVER).dll
 TARGET_XSHLDFLAGS= -shared -fPIC -Wl,-soname,$(TARGET_SONAME)
 TARGET_DYNXLDOPTS=
@@ -280,10 +281,8 @@ ifeq (Darwin,$(TARGET_SYS))
   TARGET_STRIP+= -x
   TARGET_AR+= 2>/dev/null
   TARGET_XSHLDFLAGS= -dynamiclib -single_module -undefined dynamic_lookup -fPIC
-  ifneq (,$(TARGET_DYNXLDOPTS))
-    TARGET_DYNXLDOPTS=
-    TARGET_XSHLDFLAGS+= -install_name $(PREFIX)/lib/$(TARGET_DYLIBNAME)
-  endif
+  TARGET_DYNXLDOPTS=
+  TARGET_XSHLDFLAGS+= -install_name $(TARGET_DYLIBPATH) -compatibility_version $(MAJVER).$(MINVER) -current_version $(MAJVER).$(MINVER).$(RELVER)
   ifeq (x64,$(TARGET_CCARCH))
     TARGET_XLDFLAGS+= -pagezero_size 10000 -image_base 100000000
     TARGET_XSHLDFLAGS+= -image_base 7fff04c4a000
@@ -293,10 +292,8 @@ ifeq (iOS,$(TARGET_SYS))
   TARGET_STRIP+= -x
   TARGET_AR+= 2>/dev/null
   TARGET_XSHLDFLAGS= -dynamiclib -single_module -undefined dynamic_lookup -fPIC
-  ifneq (,$(TARGET_DYNXLDOPTS))
-    TARGET_DYNXLDOPTS=
-    TARGET_XSHLDFLAGS+= -install_name $(PREFIX)/lib/$(TARGET_DYLIBNAME)
-  endif
+  TARGET_DYNXLDOPTS=
+  TARGET_XSHLDFLAGS+= -install_name $(TARGET_DYLIBPATH) -compatibility_version $(MAJVER).$(MINVER) -current_version $(MAJVER).$(MINVER).$(RELVER)
 else
   ifneq (SunOS,$(TARGET_SYS))
     TARGET_XLDFLAGS+= -Wl,-E