if cygwin bails out with weird errors while building gcc on win9x, try this
hack:

/usr/include/winnt.h:line 2061-2064

change:

typedef struct _IMAGE_IMPORT_BY_NAME {
   WORD Hint;
   BYTE Name[1];
} IMAGE_IMPORT_BY_NAME,*PIMAGE_IMPORT_BY_NAME;

to:

typedef struct _IMAGE_IMPORT_BY_NAME {
/*    WORD Hint;    */
	BYTE Name[1];
} IMAGE_IMPORT_BY_NAME,*PIMAGE_IMPORT_BY_NAME;

added: alternative fix by Fulg (Benoit Miller - fulg@iname.com)

typedef struct _IMAGE_IMPORT_BY_NAME {
   unsigned short Hint;
   unsigned char Name[1];
} IMAGE_IMPORT_BY_NAME,*PIMAGE_IMPORT_BY_NAME;

you should really remember to change that back to how it was after you compiled
gcc with success (or not? ;=P)

This is more like a dirty workaround than a fix !