feat: native GCC - cc1, cc1plus and the gcc driver run on MontaukOS

Cross-build GCC 14.2.0 with --host=x86_64-montauk: the driver, cc1,
cc1plus and collect2 now link as static Montauk ET_EXEC binaries
against the hosted libstdc++, and ship in the SDK. Together with the
native binutils, TCC and the target sysroot, MontaukOS carries a
complete self-contained C and C++ toolchain at 0:/sdk.

libc: anonymous mmap/munmap over SYS_ALLOC (GCC's page allocator
wants mmap; SYS_ALLOC memory is page-aligned by construction),
getpagesize, minimal sysconf, MB_CUR_MAX, isascii/toascii, POSIX id
typedefs (ino_t, dev_t, nlink_t, ...), struct stat fields switched to
proper POSIX types (st_size is a signed off_t now), and a
conventional _STDIO_H guard marker so GMP's FILE detection works.

Build recipe and the five host-build gotchas (bundled config.subs,
gettext removal, stdio guard sniffing, endianness cache preset,
sysroot sdk symlink) are documented in toolchain/README.md. The
devkit stages the driver as gcc.elf/g++.elf/cpp.elf, the backends in
the libexec layout the driver expects, a copy of ld where collect2
searches, and a 0:/tmp scratch dir. Ramdisk: 1604 files, 368 MB.

Co-Authored-By: Claude Fable 5 <[email protected]>

programs/include/libc/ctype.h

@@ -16,6 +16,9 @@ int islower(int c);
 int isprint(int c);
 int ispunct(int c);
 int isxdigit(int c);
+
+#define isascii(c) (((c) & ~0x7F) == 0)
+#define toascii(c) ((c) & 0x7F)
 int iscntrl(int c);
 int isgraph(int c);
 int toupper(int c);

programs/include/libc/stdio.h

@@ -1,6 +1,12 @@
 #ifndef _LIBC_STDIO_H
 #define _LIBC_STDIO_H
 
+/* Conventional guard marker: packages like GMP sniff the libc's stdio
+   include-guard name to detect that FILE is available. */
+#ifndef _STDIO_H
+#define _STDIO_H 1
+#endif
+
 #pragma once
 
 #include <stdarg.h>

programs/include/libc/stdlib.h

@@ -62,6 +62,8 @@ int                mkstemp(char *template_);
 char              *mktemp(char *template_);
 char              *realpath(const char *path, char *resolved);
 size_t             mbstowcs(wchar_t *dst, const char *src, size_t n);
+#define MB_CUR_MAX 1
+
 int                mblen(const char *s, size_t n);
 int                mbtowc(wchar_t *pwc, const char *s, size_t n);
 int                wctomb(char *s, wchar_t wc);

programs/include/libc/sys/mman.h

@@ -0,0 +1,41 @@
+#ifndef _LIBC_SYS_MMAN_H
+#define _LIBC_SYS_MMAN_H
+
+#pragma once
+
+#include <sys/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+    * Anonymous-memory mmap over SYS_ALLOC. SYS_ALLOC returns
+    * page-aligned process memory, which is exactly what callers like
+    * GCC's page allocator need. File-backed mappings are not
+    * supported and fail with ENODEV.
+*/
+
+#define PROT_NONE  0
+#define PROT_READ  1
+#define PROT_WRITE 2
+#define PROT_EXEC  4
+
+#define MAP_SHARED    0x01
+#define MAP_PRIVATE   0x02
+#define MAP_FIXED     0x10
+#define MAP_ANONYMOUS 0x20
+#define MAP_ANON      MAP_ANONYMOUS
+
+#define MAP_FAILED ((void *)-1)
+
+void *mmap(void *addr, size_t length, int prot, int flags, int fd,
+           long offset);
+int   munmap(void *addr, size_t length);
+int   mprotect(void *addr, size_t length, int prot);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _LIBC_SYS_MMAN_H */

programs/include/libc/sys/stat.h

@@ -39,18 +39,18 @@ extern "C" {
 #define S_IXOTH 0001
 
 struct stat {
-    unsigned long st_dev;
-    unsigned long st_ino;
-    mode_t        st_mode;
-    unsigned long st_nlink;
-    uid_t         st_uid;
-    gid_t         st_gid;
-    unsigned long st_size;
-    unsigned long st_blksize;
-    unsigned long st_blocks;
-    time_t        st_atime;
-    time_t        st_mtime;
-    time_t        st_ctime;
+    dev_t     st_dev;
+    ino_t     st_ino;
+    mode_t    st_mode;
+    nlink_t   st_nlink;
+    uid_t     st_uid;
+    gid_t     st_gid;
+    off_t     st_size;
+    blksize_t st_blksize;
+    blkcnt_t  st_blocks;
+    time_t    st_atime;
+    time_t    st_mtime;
+    time_t    st_ctime;
 };
 
 int    mkdir(const char *path, unsigned int mode);

programs/include/libc/sys/types.h

@@ -21,6 +21,13 @@ typedef unsigned int  mode_t;
 typedef unsigned int  uid_t;
 typedef unsigned int  gid_t;
 typedef long          time_t;
+typedef unsigned long ino_t;
+typedef unsigned long dev_t;
+typedef unsigned long nlink_t;
+typedef long          blkcnt_t;
+typedef long          blksize_t;
+typedef long          suseconds_t;
+typedef int           clockid_t;
 
 #ifdef __cplusplus
 }

programs/include/libc/unistd.h

@@ -39,6 +39,14 @@ int    execve(const char *path, char *const argv[], char *const envp[]);
 int    execvp(const char *file, char *const argv[]);
 int    pipe(int fds[2]);
 long   pathconf(const char *path, int name);
+int    getpagesize(void);
+long   sysconf(int name);
+
+/* sysconf() names (Linux numbering). */
+#define _SC_OPEN_MAX         4
+#define _SC_PAGESIZE         30
+#define _SC_PAGE_SIZE        30
+#define _SC_NPROCESSORS_ONLN 84
 
 /* pathconf() names (Linux numbering). */
 #define _PC_LINK_MAX  0