[machdep] Improve YAML generation for archs with incomplete C stdlib

Basically fields corresponding to undefined macros will properly be
associated to null instead of the macro name itself.

We do it even for macros that are supposedly defined by a standard compliant
C library, so that we can cope with more exotic implementations

share/machdeps/machdep_avr_16.yaml

@@ -713,8 +713,8 @@ errno:
     etimedout: ((int)(66072050 & 0xffff))
     ewouldblock: ((int)(66072050 & 0xffff))
     exdev: ((int)(66072050 & 0xffff))
-filename_max: FILENAME_MAX
-fopen_max: FOPEN_MAX
+filename_max: null
+fopen_max: null
 has__builtin_va_list: true
 host_name_max: '64'
 int_fast16_t: int
@@ -722,7 +722,7 @@ int_fast32_t: long
 int_fast64_t: long long
 int_fast8_t: signed char
 intptr_t: int
-l_tmpnam: L_tmpnam
+l_tmpnam: null
 little_endian: true
 machdep_name: machdep_avr_16
 mb_cur_max: ((size_t)16)
@@ -745,7 +745,7 @@ sizeof_short: 2
 sizeof_void: 1
 ssize_t: ''
 time_t: unsigned long
-tmp_max: TMP_MAX
+tmp_max: null
 tty_name_max: '32'
 uint_fast16_t: unsigned int
 uint_fast32_t: unsigned long

share/machdeps/machdep_avr_8.yaml

@@ -712,8 +712,8 @@ errno:
     etimedout: ((int)(66072050 & 0xffff))
     ewouldblock: ((int)(66072050 & 0xffff))
     exdev: ((int)(66072050 & 0xffff))
-filename_max: FILENAME_MAX
-fopen_max: FOPEN_MAX
+filename_max: null
+fopen_max: null
 has__builtin_va_list: true
 host_name_max: '64'
 int_fast16_t: int
@@ -721,7 +721,7 @@ int_fast32_t: long
 int_fast64_t: long long
 int_fast8_t: signed char
 intptr_t: int
-l_tmpnam: L_tmpnam
+l_tmpnam: null
 little_endian: true
 machdep_name: machdep_avr_8
 mb_cur_max: ((size_t)16)
@@ -744,7 +744,7 @@ sizeof_short: 2
 sizeof_void: 1
 ssize_t: ''
 time_t: unsigned long
-tmp_max: TMP_MAX
+tmp_max: null
 tty_name_max: '32'
 uint_fast16_t: unsigned int
 uint_fast32_t: unsigned long

share/machdeps/make_machdep/errno.c

@@ -23,9 +23,15 @@
 #include <errno.h>
 
 /* Mandatory */
+#ifdef EDOM
 int edom_is = EDOM;
+#endif
+#ifdef EILSEQ
 int eilseq_is = EILSEQ;
+#endif
+#ifdef ERANGE
 int erange_is = ERANGE;
+#endif
 
 /* Implementation defined by POSIX and GNU Linux */
 #ifdef E2BIG

share/machdeps/make_machdep/limits_macros.c

@@ -22,6 +22,14 @@
 
 #include <limits.h>
 
+#if defined(PATH_MAX)
 int path_max_is = PATH_MAX;
+#endif
+
+#if defined(TTY_NAME_MAX)
 int tty_name_max_is = TTY_NAME_MAX;
+#endif
+
+#if defined(HOST_NAME_MAX)
 int host_name_max_is = HOST_NAME_MAX;
+#endif

share/machdeps/make_machdep/posix_version.c

@@ -22,7 +22,7 @@
 
 #include <unistd.h>
 
-#ifdef _POSIX_VERSION
+#if defined(_POSIX_VERSION)
 long posix_version_is = _POSIX_VERSION;
 #else
 #error "not a posix arch"

share/machdeps/make_machdep/stdio_macros.c

@@ -22,9 +22,21 @@
 
 #include <stdio.h>
 
+#if defined(BUFSIZ)
 int bufsiz_is = BUFSIZ;
+#endif
+#if defined(EOF)
 int eof_is = EOF;
+#endif
+#if defined(FOPEN_MAX)
 int fopen_max_is = FOPEN_MAX;
+#endif
+#if defined(FILENAME_MAX)
 int filename_max_is = FILENAME_MAX;
+#endif
+#if defined(L_tmpnam)
 int l_tmpnam_is = L_tmpnam;
+#endif
+#if defined(TMP_MAX)
 int tmp_max_is = TMP_MAX;
+#endif

share/machdeps/make_machdep/stdlib_macros.c

@@ -23,9 +23,14 @@
 #include <limits.h>
 #include <stdlib.h>
 
+#if defined(RAND_MAX)
 int rand_max_is = RAND_MAX;
+#endif
+
 /* NB: MB_LEN_MAX is the maximal value of MB_CUR_MAX;
    however, the current Frama-C libc is not equipped to
    fully deal with a non-constant MB_CUR_MAX
 */
+#if defined(MB_LEN_MAX)
 size_t mb_cur_max_is = ((size_t)MB_LEN_MAX);
+#endif

share/machdeps/make_machdep/weof.c

@@ -22,4 +22,6 @@
 
 #include <wchar.h>
 
+#if defined(WEOF)
 const wint_t weof_is = WEOF;
+#endif

share/machdeps/make_machdep/wordsize.c

@@ -21,4 +21,7 @@
 /**************************************************************************/
 
 #include <features.h>
+
+#if defined(__WORDSIZE)
 const int wordsize_is = __WORDSIZE;
+#endif