don't install Typeable.h, fixes #1106

Author: Simon Marlow

include/Makefile

@@ -7,7 +7,12 @@ include $(TOP)/mk/boilerplate.mk
 H_FILES = $(wildcard *.h)
 
 includedir = $(libdir)/include
-INSTALL_INCLUDES = $(H_FILES)
+
+# Typeable.h doesn't need to be installed, and in fact it'll clobber the
+# Typeable.h from package base (which arguably doesn't need to be installed
+# either, but apparently some people use it...).  See bug #1106.  The Cabal
+# description for network already does the right thing here.
+INSTALL_INCLUDES = $(filter-out Typeable.h,$(H_FILES))
 
 DIST_CLEAN_FILES += HsNetworkConfig.h