Add t/deps/basic, to test basic autodependency behaviour.

Unfortunately it failed before the previous patch, so that's why this test
is needed :(

The test is a little ugly, because the bug I'm testing for didn't happen
except if you ran 'redo' two times in a row, not two times inside the same
redo session.  That's because dependency caching inside the one session
prevents the accidental rebuild.

t/deps/basic/.gitignore

@@ -0,0 +1,2 @@
+*.log
+*.out

t/deps/basic/1.in

@@ -0,0 +1 @@
+this is 1

t/deps/basic/2.in

@@ -0,0 +1 @@
+this is 2

t/deps/basic/default.out.do

@@ -0,0 +1,3 @@
+redo-ifchange $1.in
+echo $$
+echo $$ >>$1.log

t/deps/basic/test.do

@@ -0,0 +1,12 @@
+rm -f *.out *.log
+
+. ../../flush-cache.sh
+redo-ifchange 1.out 2.out
+[ "$(cat 1.log | wc -l)" = 1 ] || exit 55
+[ "$(cat 2.log | wc -l)" = 1 ] || exit 56
+. ../../flush-cache.sh
+touch 1.in
+redo-ifchange 1.out 2.out
+[ "$(cat 1.log | wc -l)" = 2 ] || exit 57
+[ "$(cat 2.log | wc -l)" = 1 ] || exit 58
+