Using checks of the existence of HEADER_{foo}_H in other header files
was a really bad idea.  For example, the following:

	#include <x509.h>
	#include <bio.h>
	#include <asn1.h>

would make sure that things like ASN1_UTCTIME_print() wasn't defined
unless you moved the inclusion of bio.h to above the inclusion of
x509.h.  The reason is that x509.h includes asn1.h, and the
declaration of ASN1_UTCTIME_print() depended on the definition of
HEADER_BIO_H.  That's what I call an obscure bug.

Instead, this change makes sure that whatever header files are needed
for the correct process of one header file are included automagically,
and that the definitions of, for example, BIO-related things are
dependent on the absence of the NO_{foo} macros.  This is also
consistent with the way parts of OpenSSL can be excluded at will.

ssl/ssl.h

diff --git a/ssl/ssl.h b/ssl/ssl.h
index 16fe694..7c60bb7 100644
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -59,6 +59,15 @@
 #ifndef HEADER_SSL_H 
 #define HEADER_SSL_H 
 
+#ifndef NO_COMP
+#include <openssl/comp.h>
+#endif
+#ifndef NO_BIO
+#include <openssl/bio.h>
+#endif
+#ifndef NO_X509
+#include <openssl/x509.h>
+#endif
 #include <openssl/safestack.h>
 
 #ifdef  __cplusplus
@@ -385,7 +394,7 @@
 {
     int id;
     char *name;
-#ifdef HEADER_COMP_H
+#ifndef NO_COMP
     COMP_METHOD *method;
 #else
     char *method;
@@ -603,7 +612,7 @@
 	 * same.  This is so data can be read and written to different
 	 * handlers */
 
-#ifdef HEADER_BIO_H
+#ifndef NO_BIO
 	BIO *rbio; /* used by SSL_read */
 	BIO *wbio; /* used by SSL_write */
 	BIO *bbio; /* used during session-id reuse to concatinate
@@ -667,7 +676,7 @@
 
 	EVP_CIPHER_CTX *enc_read_ctx;		/* cryptographic state */
 	const EVP_MD *read_hash;		/* used for mac generation */
-#ifdef HEADER_COMP_H
+#ifndef NO_COMP
 	COMP_CTX *expand;			/* uncompress */
 #else
 	char *expand;
@@ -675,7 +684,7 @@
 
 	EVP_CIPHER_CTX *enc_write_ctx;		/* cryptographic state */
 	const EVP_MD *write_hash;		/* used for mac generation */
-#ifdef HEADER_COMP_H
+#ifndef NO_COMP
 	COMP_CTX *compress;			/* compression */
 #else
 	char *compress;	
@@ -961,7 +970,7 @@
 #define SSL_add_dir_cert_subjects_to_stack SSL_add_dir_cert_sub_to_stack
 #endif
 
-#ifdef HEADER_BIO_H
+#ifndef NO_BIO
 BIO_METHOD *BIO_f_ssl(void);
 BIO *BIO_new_ssl(SSL_CTX *ctx,int client);
 BIO *BIO_new_ssl_connect(SSL_CTX *ctx);
@@ -998,7 +1007,7 @@
 int	SSL_set_rfd(SSL *s, int fd);
 int	SSL_set_wfd(SSL *s, int fd);
 #endif
-#ifdef HEADER_BIO_H
+#ifndef NO_BIO
 void	SSL_set_bio(SSL *s, BIO *rbio,BIO *wbio);
 BIO *	SSL_get_rbio(SSL *s);
 BIO *	SSL_get_wbio(SSL *s);
@@ -1053,7 +1062,7 @@
 #ifndef NO_FP_API
 int	SSL_SESSION_print_fp(FILE *fp,SSL_SESSION *ses);
 #endif
-#ifdef HEADER_BIO_H
+#ifndef NO_BIO
 int	SSL_SESSION_print(BIO *fp,SSL_SESSION *ses);
 #endif
 void	SSL_SESSION_free(SSL_SESSION *ses);
@@ -1249,7 +1258,7 @@
 					   int keylength));
 #endif
 
-#ifdef HEADER_COMP_H
+#ifndef NO_COMP
 int SSL_COMP_add_compression_method(int id,COMP_METHOD *cm);
 #else
 int SSL_COMP_add_compression_method(int id,char *cm);