Clean up Makefile logic

Makefile

@@ -143,9 +143,7 @@ endif
 
 ifeq ($(uname_S),FreeBSD)
   LDFLAGS += -lm
-endif
-
-ifeq ($(UNAME_S),SunOS)
+else ifeq ($(UNAME_S),SunOS)
   ifeq ($(shell $(CC) -V 2>&1 | grep -iq 'sun\|studio' && echo true),true)
     SUN_SHARED_FLAG = -G
   else
@@ -154,9 +152,7 @@ ifeq ($(UNAME_S),SunOS)
   REAL_LDFLAGS += -ldl -lnsl -lsocket
   DYLIB_MAKE_CMD = $(CC) $(OPTIMIZATION) $(SUN_SHARED_FLAG) -o $(DYLIBNAME) -h $(DYLIB_MINOR_NAME) $(LDFLAGS)
   SSL_DYLIB_MAKE_CMD = $(CC) $(SUN_SHARED_FLAG) -o $(SSL_DYLIBNAME) -h $(SSL_DYLIB_MINOR_NAME) $(LDFLAGS) $(SSL_LDFLAGS)
-endif
-
-ifeq ($(uname_S),Darwin)
+else ifeq ($(uname_S),Darwin)
   DYLIBSUFFIX=dylib
   DYLIB_MINOR_NAME=$(LIBNAME).$(LIBVALKEY_SONAME).$(DYLIBSUFFIX)
   DYLIB_MAKE_CMD=$(CC) -dynamiclib -Wl,-install_name,$(PREFIX)/$(LIBRARY_PATH)/$(DYLIB_MINOR_NAME) -o $(DYLIBNAME) $(LDFLAGS)