Document use of "init" in build-spec.txt, and make build.c print a

tools/build-spec.txt

+			Spec file format
+			----------------
+
 name	NAME
 type    win16|win32
 [file   WINFILENAME]
 [base   ORDINAL]
 [heap   SIZE]
+[init	FUNCTION]
 [import DLL]
 
 ORDINAL VARTYPE EXPORTNAME (DATA [DATA [DATA [...]]])
@@ -36,6 +40,9 @@ modules); default is no local heap.
 builtin. <name>.DLL is assumed if none is given. (This is important
 for kernel, which lives in the Windows file KRNL386.EXE).
 
+"init" specifies a function which will be called when this dll
+is loaded. This is only valid for Win32 modules.
+
 "import" names a module that this one depends on (only for Win32
 modules at the present). The import declaration can be present several
 times.

tools/build.c

@@ -749,8 +749,17 @@ static int ParseTopLevel(void)
         else if (strcmp(token, "init") == 0)
         {
             strcpy(DLLInitFunc, GetToken());
+	    if (SpecType == SPEC_WIN16)
+            {
+		fprintf(stderr, "%s:%d: init cannot be used for Win16 spec files\n",
+                        SpecName, Line);
+                return -1;
+            }
             if (!DLLInitFunc[0])
+            {
                 fprintf(stderr, "%s:%d: Expected function name after init\n", SpecName, Line);
+                return -1;
+            }
         }
         else if (strcmp(token, "import") == 0)
         {