Introduce scripts to run all possible tests

In 6e7d089 we added better travis continuous integration tests. This is nice,
but has two problems:
- We run only a subset of interesting tests.
- The travis builds can take hours to give us back results (especially on OS X).

This adds scripts/gen_run_tests.py, and its output, run_tests.sh, which builds
and runs a larger portion of possible configurations on the local machine.

While a travis run takes several hours to complete , I can run these scripts on
my (OS X) latop and (Linux) devserve, and get a more exhaustive set of results
back in around 10 minutes.

run_tests.sh

@@ -0,0 +1 @@
+$(dirname "$)")/scripts/gen_run_tests.py | bash

scripts/gen_run_tests.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python
+
+from itertools import combinations
+
+def powerset(items):
+    result = []
+    for i in xrange(len(items) + 1):
+        result += combinations(items, i)
+    return result
+
+MAKE_J_VAL = 32
+
+possible_compilers = [('gcc', 'g++'), ('clang', 'clang++')]
+possible_compiler_opts = [
+    '-m32',
+]
+possible_config_opts = [
+    '--enable-debug',
+    '--enable-prof',
+    '--disable-stats',
+    '--disable-tcache',
+]
+
+print 'set -e'
+print 'autoconf'
+print 'unamestr=`uname`'
+
+for cc, cxx in possible_compilers:
+    for compiler_opts in powerset(possible_compiler_opts):
+        for config_opts in powerset(possible_config_opts):
+            config_line = (
+                './configure '
+                + 'CC="{} {}" '.format(cc, " ".join(compiler_opts))
+                + 'CXX="{} {}" '.format(cxx, " ".join(compiler_opts))
+                + " ".join(config_opts)
+            )
+            # Heap profiling is not supported on OS X.
+            if '--enable-prof' in config_opts:
+                print 'if [[ "$unamestr" != "Darwin" ]]; then'
+            print config_line
+            print "make clean"
+            print "make -j" + str(MAKE_J_VAL) + " check"
+            if '--enable-prof' in config_opts:
+                print 'fi'