Configure: added "build" target.

The "build" target introduced to do all build-related tasks, and
it is now used in Makefile and in objs/Makefile as a dependency for
the "install" target.

In particular, this resolves problems as observed with dynamic modules
by people trying to do "make install" without calling "make" first.
diff --git a/auto/install b/auto/install
index 4dcc743..9469a49 100644
--- a/auto/install
+++ b/auto/install
@@ -104,8 +104,7 @@
 		-e "s|%%ERROR_LOG_PATH%%|${NGX_ERROR_LOG_PATH:-stderr}|" \\
 		< $NGX_MAN > \$@
 
-install:	$NGX_OBJS${ngx_dirsep}nginx${ngx_binext} \
-		$NGX_INSTALL_PERL_MODULES
+install:	build $NGX_INSTALL_PERL_MODULES
 	test -d '\$(DESTDIR)$NGX_PREFIX' || mkdir -p '\$(DESTDIR)$NGX_PREFIX'
 
 	test -d '\$(DESTDIR)`dirname "$NGX_SBIN_PATH"`' \
@@ -187,8 +186,6 @@
 
 build:
 	\$(MAKE) -f $NGX_MAKEFILE
-	\$(MAKE) -f $NGX_MAKEFILE modules
-	\$(MAKE) -f $NGX_MAKEFILE manpage
 
 install:
 	\$(MAKE) -f $NGX_MAKEFILE install
diff --git a/auto/make b/auto/make
index 039a70f..560924b 100644
--- a/auto/make
+++ b/auto/make
@@ -223,6 +223,10 @@
 
 cat << END                                                    >> $NGX_MAKEFILE
 
+build:	binary modules manpage
+
+binary:	$NGX_OBJS${ngx_dirsep}nginx${ngx_binext}
+
 $NGX_OBJS${ngx_dirsep}nginx${ngx_binext}:	$ngx_deps$ngx_spacer
 	\$(LINK) ${ngx_long_start}${ngx_binout}$NGX_OBJS${ngx_dirsep}nginx$ngx_long_cont$ngx_objs$ngx_libs$ngx_link$ngx_main_link
 	$ngx_rcc