Respect CFLAGS, no -Werror, allow override of destinations for e.g. Prefix,
and call pkg-config while respecting ${PKG_CONFIG} (to find ncurses libs for
e.g. tinfo).
--- a/Makefile
+++ b/Makefile
@@ -2,21 +2,20 @@
 # Note on my Mobile Pentium II, -march=pentium2 delivers twice the performance of i386
 #OptDbg=-O3
 #OptDbg=-O3 -march=pentium2
-OptDbg=-ggdb
 ifndef CWFLAGS
-CWFLAGS=-Wall -Werror -Wstrict-prototypes -Wextra -Wno-unused-parameter -Wno-missing-field-initializers
+CWFLAGS=-Wall -Wstrict-prototypes -Wextra -Wno-unused-parameter -Wno-missing-field-initializers
 endif
-CFLAGS=$(OptDbg) -I. $(CWFLAGS)
+CFLAGS+= -I. $(CWFLAGS)
 
-PREFIX  = /usr
+PREFIX  ?= /usr
 # STRIP = -s
-INSTALL = /usr/bin/install
-DESTDIR =
-BINDIR  = $(PREFIX)/bin
-MANDIR  = $(PREFIX)/share/man
-MAN1DIR = $(MANDIR)/man1
-MAN5DIR = $(MANDIR)/man5
-LDLIBS = -lncurses
+INSTALL ?= /usr/bin/install
+DESTDIR ?=
+BINDIR  ?= $(PREFIX)/bin
+MANDIR  ?= $(PREFIX)/share/man
+MAN1DIR ?= $(MANDIR)/man1
+MAN5DIR ?= $(MANDIR)/man5
+LDLIBS = $(shell $${PKG_CONFIG:-pkg-config} --libs ncurses)
 
 all: wiggle wiggle.man test