Rename zero_realloc option "strict" to "alloc".

With realloc(ptr, 0) being UB per C23, the option name "strict" makes less sense
now.  Rename to "alloc" which describes the behavior.

include/jemalloc/internal/jemalloc_internal_types.h

@@ -9,7 +9,7 @@ typedef int malloc_cpuid_t;
 /* When realloc(non-null-ptr, 0) is called, what happens? */
 enum zero_realloc_action_e {
 	/* Realloc(ptr, 0) is free(ptr); return malloc(0); */
-	zero_realloc_action_strict = 0,
+	zero_realloc_action_alloc = 0,
 	/* Realloc(ptr, 0) is free(ptr); */
 	zero_realloc_action_free = 1,
 	/* Realloc(ptr, 0) aborts. */