autotools: provide smaller EOLIAN_FLAGS for customization

src/Makefile.am

@@ -2,6 +2,8 @@ MAINTAINERCLEANFILES = Makefile.in
 CLEANFILES =
 BUILT_SOURCES =
 
+EOLIAN_FLAGS = -I$(srcdir)
+
 DIST_SUBDIRS =
 SUBDIRS =
 

src/Makefile_Elua_Helper.am

@@ -20,6 +20,6 @@ am__v_ELUA_0 = @echo "  ELUA    " $@;
 SUFFIXES += .lua
 
 %.eo.lua: %.eo ${_ELUA_GEN_DEP}
-	$(AM_V_ELUA)$(ELUA_GEN) -I$(srcdir) -o $@ $<
+	$(AM_V_ELUA)$(ELUA_GEN) $(EOLIAN_FLAGS) -o $@ $<
 
 CLEANFILES += $(BUILT_SOURCES)

src/Makefile_Eolian_Cxx_Helper.am

@@ -15,6 +15,6 @@ SUFFIXES += .eo.hh
 %.eo.impl.hh %.eo.hh: %.eo $(_EOLIAN_CXX_DEP)
 	$(AM_V_EOLCXX) \
 	$(MKDIR_P) $(dir $@); \
-	$(EOLIAN_CXX) -I$(srcdir) -o $@ $<
+	$(EOLIAN_CXX) $(EOLIAN_FLAGS) -o $@ $<
 
 CLEANFILES += $(BUILT_SOURCES)

src/Makefile_Eolian_Helper.am

@@ -15,21 +15,21 @@ SUFFIXES = .eo .eo.c .eo.h .eo.legacy.h .eot .eot.h
 %.eo.c: %.eo ${_EOLIAN_GEN_DEP}
 	$(AM_V_EOL) \
 	$(MKDIR_P) $(dir $@); \
-	$(EOLIAN_GEN) --eo --legacy -I$(srcdir) --gc -o $@ $<
+	$(EOLIAN_GEN) --eo --legacy $(EOLIAN_FLAGS) --gc -o $@ $<
 
 %.eo.h: %.eo ${_EOLIAN_GEN_DEP}
 	$(AM_V_EOL) \
 	$(MKDIR_P) $(dir $@); \
-	$(EOLIAN_GEN) --eo -I$(srcdir) --gh -o $@ $<
+	$(EOLIAN_GEN) --eo $(EOLIAN_FLAGS) --gh -o $@ $<
 
 %.eot.h: %.eot ${_EOLIAN_GEN_DEP}
 	$(AM_V_EOL) \
 	$(MKDIR_P) $(dir $@); \
-	$(EOLIAN_GEN) --eo -I$(srcdir) --gh -o $@ $<
+	$(EOLIAN_GEN) --eo $(EOLIAN_FLAGS) --gh -o $@ $<
 
 %.eo.legacy.h: %.eo ${_EOLIAN_GEN_DEP}
 	$(AM_V_EOL) \
 	$(MKDIR_P) $(dir $@); \
-	$(EOLIAN_GEN) --legacy -I$(srcdir) --gh -o $@ $<
+	$(EOLIAN_GEN) --legacy $(EOLIAN_FLAGS) --gh -o $@ $<
 
 CLEANFILES += $(BUILT_SOURCES)