Make tests work on Solaris: - replacement for mktemp - fall back if shell arithmetic doesn't work - replacement for 'set -x' (which results look different with some shells) - "FOO=bar; export FOO" instead of "export FOO=bar" - don't use 'if ! ...'

diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123