Use shell MAKE variable to allow parallel builds.
Index: fbreader/Makefile
===================================================================
--- fbreader.orig/Makefile	2009-03-29 18:33:45.941040634 +0300
+++ fbreader/Makefile	2009-03-29 18:34:50.481041319 +0300
@@ -21,21 +21,21 @@
 do_install:
 	@for dir in $(ZLIBDIRS) $(APPDIRS); do \
 		if [ -d $$dir ]; then \
-			cd $$dir; make $@; cd $(ROOTDIR); \
+			cd $$dir; $(MAKE) $@; cd $(ROOTDIR); \
 		fi; \
 	done
 
 do_install_dev:
 	@for dir in $(ZLIBDIRS); do \
 		if [ -d $$dir ]; then \
-			cd $$dir; make $@; cd $(ROOTDIR); \
+			cd $$dir; $(MAKE) $@; cd $(ROOTDIR); \
 		fi; \
 	done
 
 clean:
 	@for dir in $(ZLIBDIRS) $(APPDIRS); do \
 		if [ -d $$dir ]; then \
-			cd $$dir; make $@; cd $(ROOTDIR); \
+			cd $$dir; $(MAKE) $@; cd $(ROOTDIR); \
 		fi; \
 	done
 
Index: fbreader/fbreader/Makefile
===================================================================
--- fbreader.orig/fbreader/Makefile	2009-03-29 18:33:45.957035125 +0300
+++ fbreader/fbreader/Makefile	2009-03-29 18:34:50.481041319 +0300
@@ -55,13 +55,13 @@
 	@install -m 0644 $(wildcard data/icons/toolbar/$(VARIANT)/*.*) $(DESTDIR)$(APPIMAGEDIR_REAL)
 	@install -m 0644 $(wildcard data/icons/filetree/$(VARIANT)/*.*) $(DESTDIR)$(APPIMAGEDIR_REAL)
 	@install -m 0644 $(wildcard data/icons/booktree/$(VARIANT)/*.*) $(DESTDIR)$(APPIMAGEDIR_REAL)
-	@make -C $(TARGET_ARCH) RESOLUTION=$(RESOLUTION) install
+	@$(MAKE) -C $(TARGET_ARCH) RESOLUTION=$(RESOLUTION) install
 
 clean:
 	@for subdir in $(ALL_SUBDIRS); do \
 		$(MAKE) -C $$subdir -f $(MAKEFILESDIR)/subdir.mk clean; \
 	done;
 	@for subdir in $(ALL_ARCHSUBDIRS); do \
-		cd $$subdir; make clean; cd ..; \
+		cd $$subdir; $(MAKE) clean; cd ..; \
 	done;
 	@$(RM) $(TARGET) err
Index: fbreader/zlibrary/core/Makefile
===================================================================
--- fbreader.orig/zlibrary/core/Makefile	2009-03-29 18:33:45.973035972 +0300
+++ fbreader/zlibrary/core/Makefile	2009-03-29 18:34:50.481041319 +0300
@@ -38,7 +38,7 @@
 endif
 
 .objects:
-	@for subdir in $(SUBDIRS); do \
+	+@for subdir in $(SUBDIRS); do \
 		if [ -d $$subdir ]; then \
 			if ! $(LIBMAKE) -C $$subdir -f $(MAKEFILESDIR)/subdir.mk; then \
 				exit 1; \
Index: fbreader/zlibrary/text/Makefile
===================================================================
--- fbreader.orig/zlibrary/text/Makefile	2009-03-29 18:33:45.989033397 +0300
+++ fbreader/zlibrary/text/Makefile	2009-03-29 18:34:50.481041319 +0300
@@ -22,7 +22,7 @@
 SUBDIRS = src/model src/view src/hyphenation
 
 .objects:
-	@for subdir in $(SUBDIRS); do \
+	+@for subdir in $(SUBDIRS); do \
 		if [ -d $$subdir ]; then \
 			if ! $(LIBMAKE) -C $$subdir -f $(MAKEFILESDIR)/subdir.mk; then \
 				exit 1; \
Index: fbreader/zlibrary/ui/Makefile
===================================================================
--- fbreader.orig/zlibrary/ui/Makefile	2009-03-29 18:33:46.005032289 +0300
+++ fbreader/zlibrary/ui/Makefile	2009-03-29 18:34:50.485038965 +0300
@@ -66,21 +66,21 @@
 endif
 
 .objects:
-	@for subdir in $(SUBDIRS); do \
+	+@for subdir in $(SUBDIRS); do \
 		if [ -d $$subdir ]; then \
 			if ! $(LIBMAKE) -C $$subdir -f $(MAKEFILESDIR)/subdir.mk; then \
 				exit 1; \
 			fi; \
 		fi; \
 	done;
-	@for subdir in $(QTSUBDIRS); do \
+	+@for subdir in $(QTSUBDIRS); do \
 		if [ -d $$subdir ]; then \
 			if ! $(LIBMAKE) -C $$subdir -f $(MAKEFILESDIR)/qsubdir.mk; then \
 				exit 1; \
 			fi; \
 		fi; \
 	done;
-	@for subdir in $(GTKSUBDIRS); do \
+	+@for subdir in $(GTKSUBDIRS); do \
 		if [ -d $$subdir ]; then \
 			if ! $(LIBMAKE) -C $$subdir -f $(MAKEFILESDIR)/gtksubdir.mk; then \
 				exit 1; \