Configure: marked top-level make targets as phony.

Reported by Thibault Nélis.

auto/init

diff --git a/auto/init b/auto/init
index 910f529..f816dfc 100644
--- a/auto/init
+++ b/auto/init
@@ -48,4 +48,6 @@
 
 clean:
 	rm -rf Makefile $NGX_OBJS
+
+.PHONY:	default clean
 END

auto/install

diff --git a/auto/install b/auto/install
index d884487..c764fdd 100644
--- a/auto/install
+++ b/auto/install
@@ -215,4 +215,6 @@
 	test -f $NGX_PID_PATH.oldbin
 
 	kill -QUIT \`cat $NGX_PID_PATH.oldbin\`
+
+.PHONY:	build install modules upgrade
 END