Add the sys directory for libc functions which use system calls; move the

malloc functions in there.

lang/cem/libcc.ansi/build.lua

@@ -43,8 +43,7 @@ for _, plat in ipairs(vars.plats) do
 			"./core/math/*.e",
 			"./core/ctype/*.c",
 			"./core/misc/*.c",
-			"./errno/*.c",
-			"./malloc/*.c",
+			"./sys/malloc/*.c",
 			"./signal/*.c",
 			"./assert/*.c",
 			"./stdio/*.c",
@@ -58,7 +57,7 @@ for _, plat in ipairs(vars.plats) do
 		deps = {
 			"lang/cem/libcc.ansi/headers+pkg",
 			"plat/"..plat.."/include+pkg",
-			"./malloc/malloc.h",
+			"./sys/malloc/malloc.h",
 			"./core/math/localmath.h",
 			"./core/stdlib/ext_fmt.h",
 			"./stdio/loc_incl.h",

lang/cem/libcc.ansi/sys/README.md

@@ -0,0 +1,4 @@
+The functions here all use Posix system calls to do the actual work, and so
+require `unistd.h` (at the minimum). Typically each group of functions will
+be protected by an `ACKCONF` variable so the plat can turn them on and off as
+necessary.

lang/cem/libcc.ansi/sys/malloc/calloc.c

@@ -3,6 +3,8 @@
 #include <unistd.h>
 #include <string.h>
 
+#if ACKCONF_WANT_MALLOC
+
 void* calloc(size_t nmemb, size_t size)
 {
 	size_t bytes = nmemb * size;
@@ -22,3 +24,5 @@ void* calloc(size_t nmemb, size_t size)
 	memset(ptr, 0, bytes);
 	return ptr;
 }
+
+#endif

lang/cem/libcc.ansi/sys/malloc/malloc.c

@@ -3,6 +3,8 @@
 #include <unistd.h>
 #include "malloc.h"
 
+#if ACKCONF_WANT_MALLOC
+
 block_t __mem_root = { &__mem_root, 0 };
 block_t* __mem_freelist = &__mem_root;
 
@@ -148,3 +150,5 @@ void free(void* ptr)
 	/* ...and update the ring pointer. */
 	__mem_freelist = p;
 }
+
+#endif

lang/cem/libcc.ansi/sys/malloc/realloc.c

@@ -4,6 +4,8 @@
 #include <string.h>
 #include "malloc.h"
 
+#if ACKCONF_WANT_MALLOC
+
 void* realloc(void* ptr, size_t size)
 {
 	block_t* h;
@@ -39,3 +41,5 @@ void* realloc(void* ptr, size_t size)
 	free(ptr);
 	return newptr;
 }
+
+#endif