Add configure option to pass GHC flags

Adding the HEXTRA option to make might not be practical for a change
that should be always applied, e.g., hiding a certain package. This
patch allows the flags to be specified at the configure level.
Signed-off-by: Hrvoje Ribicic <riba@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

Makefile.am

@@ -538,6 +538,8 @@ HFLAGS = \
 HEXTRA =
 # internal extra flags (used for test/hs/htest mainly)
 HEXTRA_INT =
+# combination of HEXTRA and HEXTRA_CONFIGURE
+HEXTRA_COMBINED = $(HEXTRA) $(HEXTRA_CONFIGURE)
 # exclude options for coverage reports
 HPCEXCL = --exclude Main \
 	--exclude Ganeti.Constants \
@@ -881,7 +883,7 @@ $(HS_ALL_PROGS): %: %.hs $(HS_LIBTESTBUILT_SRCS) Makefile
 	  $(HFLAGS) \
 	  $(HS_PARALLEL3) $(HS_REGEX_PCRE) \
 	  -osuf $(notdir $@).o -hisuf $(notdir $@).hi \
-	  $(HEXTRA) $(HEXTRA_INT) $@
+	  $(HEXTRA_COMBINED) $(HEXTRA_INT) $@
 	@touch "$@"
 
 # for the test/hs/htest binary, we need to enable profiling/coverage

configure.ac

@@ -24,6 +24,15 @@ AC_SUBST([VERSION_REVISION], gnt_version_revision)
 AC_SUBST([VERSION_SUFFIX], gnt_version_suffix)
 AC_SUBST([VERSION_FULL], gnt_version_full)
 
+# --with-haskell-flags=
+AC_ARG_WITH([haskell-flags],
+  [AS_HELP_STRING([--with-haskell-flags=FLAGS],
+    [Extra flags to pass to GHC]
+  )],
+  [hextra_configure="$withval"],
+  [hextra_configure=""])
+AC_SUBST(HEXTRA_CONFIGURE, $hextra_configure)
+
 # --with-ssh-initscript=...
 AC_ARG_WITH([ssh-initscript],
   [AS_HELP_STRING([--with-ssh-initscript=SCRIPT],