core: Prepare for M2-Planet: if (foo).

Rewrite C-constructs not supported by M2-Planet

    if (foo)              -> if (foo != 0)

* src/posix.c: Rewrite C-constructs not supported by M2-Planet.
(current_input_port): Likewise.
* src/display.c (display_helper): : Likewise.
* src/eval-apply.c (expand_variable_): : Likewise.
(eval_apply): : Likewise.
* src/mes.c (open_boot): : Likewise.
* src/reader.c (reader_read_identifier_or_number): : Likewise.
* src/symbols.c (init_symbol): : Likewise.

src/display.c

@@ -115,7 +115,7 @@ display_helper (SCM x, int cont, char *sep, int fd, int write_p)
     {
       if (write_p == 0)
         fdputc (VALUE (x), fd);
-      else if (1)
+      else
         {
           fdputs ("#", fd);
           fdwrite_char (VALUE (x), fd);

src/eval-apply.c

@@ -259,7 +259,7 @@ expand_variable_ (SCM x, SCM formals, int top_p)        /*:((internal)) */
           else if (a == cell_symbol_define || a == cell_symbol_define_macro)
             {
               SCM f = CADR (x);
-              if (top_p && TYPE (f) == TPAIR)
+              if (top_p != 0 && TYPE (f) == TPAIR)
                 f = CDR (f);
               formals = add_formals (formals, f);
               x = CDR (x);
@@ -270,7 +270,7 @@ expand_variable_ (SCM x, SCM formals, int top_p)        /*:((internal)) */
                    && a != cell_symbol_boot_module
                    && a != cell_symbol_current_module
                    && a != cell_symbol_primitive_load
-                   && formal_p (a, formals))
+                   && formal_p (CAR (x), formals) == 0)
             {
               SCM v = module_variable (R0, a);
               if (v != cell_f)
@@ -671,7 +671,7 @@ eval:
                     formals = CDADR (R1);
                     body = CDDR (R1);
 
-                    if (macro_p || global_p)
+                    if (macro_p != 0 || global_p != 0)
                       expand_variable (body, formals);
                     R1 = cons (cell_symbol_lambda, cons (formals, body));
                     push_cc (R1, R2, p, cell_vm_eval_define);

src/mes.c

@@ -378,11 +378,11 @@ open_boot ()
       eputs (MES_PKGDATADIR);
       eputs ("\n");
     }
-  if (getenv ("MES_BOOT"))
+  if (getenv ("MES_BOOT") != 0)
     strcpy (boot, getenv ("MES_BOOT"));
   else
     strcpy (boot, "boot-0.scm");
-  if (getenv ("MES_PREFIX"))
+  if (getenv ("MES_PREFIX") != 0)
     {
       strcpy (g_datadir, getenv ("MES_PREFIX"));
       strcpy (g_datadir + strlen (g_datadir), "/mes");
@@ -408,7 +408,7 @@ open_boot ()
   if (__stdin < 0)
     {
       g_datadir[0] = 0;
-      if (getenv ("srcdest"))
+      if (getenv ("srcdest") != 0)
         strcpy (g_datadir, getenv ("srcdest"));
       strcpy (g_datadir + strlen (g_datadir), "mes");
       strcpy (file_name, g_datadir);

src/posix.c

@@ -193,7 +193,7 @@ current_input_port ()
   if (__stdin >= 0)
     return make_number (__stdin);
   SCM x = g_ports;
-  while (x)
+  while (x != 0)
     {
       SCM a = CAR (x);
       if (PORT (a) == __stdin)

src/reader.c

@@ -91,7 +91,7 @@ reader_read_identifier_or_number (int c)
       n = n + c - '0';
       c = readchar ();
     }
-  if (reader_end_of_word_p (c))
+  if (reader_end_of_word_p (c) != 0)
     {
       unreadchar (c);
       if (negative_p != 0)

src/symbol.c

@@ -43,7 +43,7 @@ SCM
 init_symbol (SCM x, long type, char const *name)
 {
   TYPE (x) = type;
-  if (!g_symbols)
+  if (g_symbols == 0)
     g_free = g_free + M2_CELL_SIZE;
   else
     {