Merge branch 'js/gcc-8-and-9'

Code clean-up for new compilers.

* js/gcc-8-and-9:
  config: avoid calling `labs()` on too-large data type
  winansi: simplify loading the GetCurrentConsoleFontEx() function
  kwset: allow building with GCC 8
  poll (mingw): allow compiling with GCC 8 and DEVELOPER=1

kwset.c

@@ -38,7 +38,13 @@
 #include "compat/obstack.h"
 
 #define NCHAR (UCHAR_MAX + 1)
-#define obstack_chunk_alloc xmalloc
+/* adapter for `xmalloc()`, which takes `size_t`, not `long` */
+static void *obstack_chunk_alloc(long size)
+{
+	if (size < 0)
+		BUG("Cannot allocate a negative amount: %ld", size);
+	return xmalloc(size);
+}
 #define obstack_chunk_free free
 
 #define U(c) ((unsigned char) (c))