Make the project build with Microsoft's broken C compiler.

MSVC is not fully C11-compliant, even when compiling with /std:c11.
Some changes were needed to make the codebase compatible. Notably, the
notation a[static N] and a[n] for function parameters of array type is
not supported, so that had to be hidden behind a macro.  Atomic types
are also an experimental feature, apparently, but at least they work
with the correct compiler flag.

One thing that MSVC does well, however, is warning on integer conversions
on /W4 level. I am not sure if Clang and GCC have something similar,
so I took this chance to fix some of these.

1 files changed, 2 insertions, 2 deletions

diff --git a/test/010_math_permtoindex/permtoindex_tests.c b/test/010_math_permtoindex/permtoindex_tests.c
index f246ef3..2a7ecf3 100644
--- a/test/010_math_permtoindex/permtoindex_tests.c
+++ b/test/010_math_permtoindex/permtoindex_tests.c
@@ -1,6 +1,6 @@
 #include "../test.h"
 
-uint64_t permtoindex(size_t n, const uint8_t [n]);
+uint64_t permtoindex(size_t n, const uint8_t *);
 
 void run(void) {
         char str[STRLENMAX];
@@ -11,7 +11,7 @@ void run(void) {
         n = atoll(str);
         for (i = 0; i < n; i++) {
                 fgets(str, STRLENMAX, stdin);
-                a[i] = atoi(str);
+                a[i] = (uint8_t)atoi(str);
         }
 
         p = permtoindex(n, a);