Support for Solaris default shell restriction

Some shells (like Solaris default /bin/sh) doesn't allow -e
option for file existence check. Use -f instead.

hostapd/Makefile

@@ -731,7 +731,7 @@ install: all
 	for i in $(ALL); do cp -f $$i /usr/local/bin/$$i; done
 
 ../src/drivers/build.hostapd:
-	@if [ -e ../src/drivers/build.wpa_supplicant ]; then \
+	@if [ -f ../src/drivers/build.wpa_supplicant ]; then \
 		$(MAKE) -C ../src/drivers clean; \
 	fi
 	@touch ../src/drivers/build.hostapd

wpa_supplicant/Makefile

@@ -26,7 +26,7 @@ verify_config:
 	fi
 
 mkconfig:
-	@if [ -e .config ]; then \
+	@if [ -f .config ]; then \
 		echo '.config exists - did not replace it'; \
 		exit 1; \
 	fi
@@ -1252,7 +1252,7 @@ endif
 dynamic_eap_methods: $(EAPDYN)
 
 ../src/drivers/build.wpa_supplicant:
-	@if [ -e ../src/drivers/build.hostapd ]; then \
+	@if [ -f ../src/drivers/build.hostapd ]; then \
 		$(MAKE) -C ../src/drivers clean; \
 	fi
 	@touch ../src/drivers/build.wpa_supplicant