Makefile: Fix parallel build issue

If clean runs in parallel with $(OBJECTS), it is possible to build some
objects first, then the clean target fires and deletes some, and then we
try to link and fail.

Gentoo-Bug: https://bugs.gentoo.org/528218

--- a/makefile
+++ b/makefile
@@ -3,12 +3,12 @@
 
 # Linux using GCC
 CXX=c++
-CXXFLAGS=-O2 -Wno-logical-op-parentheses -Wno-switch -Wno-dangling-else
+CXXFLAGS=$(RPM_OPT_FLAGS) -fPIC -DPIC -Wno-parentheses -Wno-switch -Wno-sign-compare -Wno-class-memaccess -Wno-unused-variable -Wno-unused-function -Wno-dangling-else
 LIBFLAGS=-fPIC
 DEFINES=-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DRAR_SMP
 STRIP=strip
 AR=ar
-LDFLAGS=-pthread
+LDFLAGS=$(RPM_LD_FLAGS) -pthread
 DESTDIR=/usr
 
 # Linux using LCC
@@ -142,21 +142,18 @@
 	@rm -f $(OBJECTS) $(UNRAR_OBJ) $(LIB_OBJ)
 	@rm -f unrar libunrar.*
 
-unrar:	clean $(OBJECTS) $(UNRAR_OBJ)
-	@rm -f unrar
+unrar:	$(OBJECTS) $(UNRAR_OBJ)
 	$(LINK) -o unrar $(LDFLAGS) $(OBJECTS) $(UNRAR_OBJ) $(LIBS)	
 	$(STRIP) unrar
 
 sfx:	WHAT=SFX_MODULE
-sfx:	clean $(OBJECTS)
-	@rm -f default.sfx
+sfx:	$(OBJECTS)
 	$(LINK) -o default.sfx $(LDFLAGS) $(OBJECTS)
 	$(STRIP) default.sfx
 
 lib:	WHAT=RARDLL
 lib:	CXXFLAGS+=$(LIBFLAGS)
-lib:	clean $(OBJECTS) $(LIB_OBJ)
-	@rm -f libunrar.*
+lib:	$(OBJECTS) $(LIB_OBJ)
 	$(LINK) -shared -o libunrar.so $(LDFLAGS) $(OBJECTS) $(LIB_OBJ)
 	$(AR) rcs libunrar.a $(OBJECTS) $(LIB_OBJ)