Revert "Split neslib and nesdoug components so they are linked condit…

…ionally (#217)"

This reverts commit 55051dd.

I gave this a quick spin-through compiling
/~https://github.com/mysterymath/nesdoug/26_Full_Game, and this change
causes it to immediately present "You Died" after hitting Start. Not
sure exactly what changed, but it looks like this introduces some kind
of significant behavioral change.

mos-platform/nes/nesdoug/CMakeLists.txt

@@ -5,13 +5,9 @@ install(FILES
 TYPE INCLUDE)
 
 add_platform_library(nes-nesdoug
-  metatile.c
-  metatile.s
   nesdoug.s
   nesdoug.c
   padlib.s
-  vram_buffer.c
-  vram_buffer.s
   zaplib.s
 )
 target_include_directories(nes-nesdoug BEFORE PUBLIC ..)

mos-platform/nes/nesdoug/nesdoug.c

@@ -7,6 +7,21 @@
 // based on code by Groepaz/Hitmen <groepaz@gmx.net>, Ullrich von Bassewitz
 // <uz@cc65.org>
 
+// Keeping these functions in C LTOs them in, which informs LTO code generation
+// that the ZP regions aren't available. This saves users of the library from
+// having to manually reserve ZP space from LTO.
+__attribute__((section(".zp.vram_index"))) char VRAM_INDEX;
+__attribute__((section(".zp.meta_ptr"))) const char *META_PTR;
+__attribute__((section(".zp.data_ptr"))) const char *DATA_PTR;
+
+extern char VRAM_BUF[];
+void set_vram_update(const void *buf);
+void set_vram_buffer(void) {
+  VRAM_BUF[0] = 0xff;
+  VRAM_INDEX = 0;
+  set_vram_update(VRAM_BUF);
+}
+
 extern char PAD_STATET[];
 char get_pad_new(char pad) { return PAD_STATET[pad]; }
 
@@ -29,6 +44,11 @@ void set_scroll_y(unsigned y) {
   PPUCTRL_VAR = PPUCTRL_VAR & 0xfd | (y >> 8 & 0x01) << 1;
 }
 
+void set_data_pointer(const void *data) { DATA_PTR = (const char *)data; }
+void set_mt_pointer(const void *metatiles) {
+  META_PTR = (const char *)metatiles;
+}
+
 extern volatile char PPUMASK_VAR;
 void color_emphasis(char color) {
   PPUMASK_VAR = PPUMASK_VAR & 0x1f | color & 0xe0;