add $(PREFIX)/include and $(PREFIX)/lib to the search paths

Makefile.in

@@ -13,12 +13,14 @@ MOC ?= moc
 RCC ?= rcc
 
 warn = -pedantic -Wall
-incdir = -I.
+incdir = -I. -I$(PREFIX)/include
+libdir = -L$(PREFIX)/lib
 
 CFLAGS = $(warn) $(dbg) $(opt) $(incdir) -fPIC $(add_cflags) -MMD
 CXXFLAGS = $(warn) $(dbg) $(opt) $(incdir) -fPIC `pkg-config --cflags Qt5Core Qt5Gui Qt5Widgets` \
 		 $(add_cflags) -MMD
-LDFLAGS = `pkg-config --libs Qt5Core Qt5Gui Qt5Widgets` -lspnav -lX11 $(add_ldflags)
+LDFLAGS = $(libdir) `pkg-config --libs Qt5Core Qt5Gui Qt5Widgets` -lspnav -lX11 \
+		  $(add_ldflags)
 
 $(bin): $(obj)
 	$(CXX) -o $@ $(obj) $(LDFLAGS)