Update support for Cygwin 2.10.0 without X11. Based on MSYS toolchain config.

config/Makefile.cygwin

@@ -4,9 +4,10 @@ GLEW_DEST ?= /usr
 CC := cc
 LD := cc
 LN :=
+CFLAGS.EXTRA += -D_WIN32
 LDFLAGS.EXTRA =
 LIBDIR = $(GLEW_DEST)/lib
-LDFLAGS.GL = -lGL -lX11
+LDFLAGS.GL = -lOpenGL32 -mwindows
 LDFLAGS.STATIC = -Wl,-Bstatic
 LDFLAGS.DYNAMIC = -Wl,-Bdynamic
 WARN = -Wall -W

config/Makefile.cygwin-x11

+NAME = GLEW
+GLEW_DEST ?= /usr
+# use gcc for linking, with ld it does not work
+CC := cc
+LD := cc
+LN :=
+LDFLAGS.EXTRA =
+LIBDIR = $(GLEW_DEST)/lib
+LDFLAGS.GL = -lGL -lX11
+LDFLAGS.STATIC = -Wl,-Bstatic
+LDFLAGS.DYNAMIC = -Wl,-Bdynamic
+WARN = -Wall -W
+POPT = -O2
+BIN.SUFFIX = .exe
+LIB.SONAME    = cyg$(NAME)-$(GLEW_MAJOR)-$(GLEW_MINOR).dll
+LIB.DEVLNK    = lib$(NAME).dll.a
+LIB.SHARED    = cyg$(NAME)-$(GLEW_MAJOR)-$(GLEW_MINOR).dll
+LIB.STATIC    = lib$(NAME).a
+LDFLAGS.SO    = -shared -Wl,--out-implib,lib/$(LIB.DEVLNK)