[CI] Hook cli-tests up to CI

Add cli-tests to `make test`. This adds a `python3` dependency to `make
test`, but not `make check`. We could make this dependency optional by
skipping the tests if `python3` is not present.

tests/cli-tests/dictionaries/dictionary-mismatch.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-source "$COMMON/platform.sh"
+. "$COMMON/platform.sh"
 
 set -e
 
@@ -22,7 +22,7 @@ if [ false ]; then
 	datagen -g1000 -s0 > file0
 fi
 
-set -x
+set -v
 zstd files/0 -D dicts/0
 zstd -t files/0.zst -D dicts/0
 zstd -t files/0.zst -D dicts/1 && die "Must fail" ||:

tests/cli-tests/dictionaries/dictionary-mismatch.sh.stderr.exact

@@ -1,8 +1,6 @@
-+ zstd files/0 -D dicts/0
-+ zstd -t files/0.zst -D dicts/0
-+ zstd -t files/0.zst -D dicts/1
+zstd files/0 -D dicts/0
+zstd -t files/0.zst -D dicts/0
+zstd -t files/0.zst -D dicts/1 && die "Must fail" ||:
 files/0.zst : Decoding error (36) : Dictionary mismatch 
-+ :
-+ zstd -t files/0.zst
+zstd -t files/0.zst            && die "Must fail" ||:
 files/0.zst : Decoding error (36) : Dictionary mismatch 
-+ :

tests/cli-tests/dictionaries/setup_once

@@ -2,7 +2,7 @@
 
 set -e
 
-source "$COMMON/platform.sh"
+. "$COMMON/platform.sh"
 
 
 mkdir files/ dicts/