Add a dependency of program modules on GHC.TopHandler

If you were unlucky, the build could fail, e.g.:

utils\mkUserGuidePart\Main.hs:1:1:
    Failed to load interface for `GHC.TopHandler'
    There are files missing in the `base' package,
    try running 'ghc-pkg check'.
    Use -v to see a list of the files searched for.
utils/mkUserGuidePart/ghc.mk:18: recipe for target `utils/mkUserGuidePart/dist/build/Main.o' failed

ghc.mk

@@ -155,6 +155,7 @@ endif
 include rules/prof.mk
 include rules/trace.mk
 include rules/library-path.mk
+include rules/add-dependency.mk
 include rules/make-command.mk
 include rules/pretty_commands.mk
 

rules/add-dependency.mk

+# -----------------------------------------------------------------------------
+#
+# (c) 2010 The University of Glasgow
+#
+# This file is part of the GHC build system.
+#
+# To understand how the build system works and how to modify it, see
+#      http://hackage.haskell.org/trac/ghc/wiki/Building/Architecture
+#      http://hackage.haskell.org/trac/ghc/wiki/Building/Modifying
+#
+# -----------------------------------------------------------------------------
+
+define add-dependency
+$1: $2
+endef

rules/build-prog.mk

@@ -246,4 +246,12 @@ endif
 
 $(call dependencies,$1,$2,$3)
 
+# The Main module of a program implicitly depends on GHC.TopHandler
+# so we need to add a dependency for that. As we don't know which
+# module contains Main, we just make all modules in the program
+# depend on it.
+ifneq "$3" "0"
+$$(foreach o,$$($1_$2_$$($1_$2_PROGRAM_WAY)_HS_OBJS),$$(eval $$(call add-dependency,$$o,libraries/base/dist-install/build/GHC/TopHandler.$$($$($1_$2_PROGRAM_WAY)_osuf))))
+endif
+
 endef