Remove some unnecessary recursive includes from the internal apps.h header,
and include bn.h in those C files that need bignum functionality.

apps/apps.c

diff --git a/apps/apps.c b/apps/apps.c
index 6925ab4..3c3a11c 100644
--- a/apps/apps.c
+++ b/apps/apps.c
@@ -126,6 +126,7 @@
 #include <openssl/engine.h>
 #endif
 #include <openssl/rsa.h>
+#include <openssl/bn.h>
 
 #define NON_MAIN
 #include "apps.h"

apps/apps.h

diff --git a/apps/apps.h b/apps/apps.h
index 6072a10..e653bf1 100644
--- a/apps/apps.h
+++ b/apps/apps.h
@@ -114,9 +114,7 @@
 
 #include "e_os.h"
 
-#include <openssl/buffer.h>
 #include <openssl/bio.h>
-#include <openssl/crypto.h>
 #include <openssl/x509.h>
 #include <openssl/lhash.h>
 #include <openssl/conf.h>

apps/dsa.c

diff --git a/apps/dsa.c b/apps/dsa.c
index e9de3a3..b6f0ed3 100644
--- a/apps/dsa.c
+++ b/apps/dsa.c
@@ -68,6 +68,7 @@
 #include <openssl/evp.h>
 #include <openssl/x509.h>
 #include <openssl/pem.h>
+#include <openssl/bn.h>
 
 #undef PROG
 #define PROG	dsa_main

apps/ocsp.c

diff --git a/apps/ocsp.c b/apps/ocsp.c
index 9c8e20d..52af592 100644
--- a/apps/ocsp.c
+++ b/apps/ocsp.c
@@ -64,6 +64,7 @@
 #include <openssl/ocsp.h>
 #include <openssl/err.h>
 #include <openssl/ssl.h>
+#include <openssl/bn.h>
 
 /* Maximum leeway in validity period: default 5 minutes */
 #define MAX_VALIDITY_PERIOD	(5 * 60)

apps/rsa.c

diff --git a/apps/rsa.c b/apps/rsa.c
index 0acdb08..afbe0b4 100644
--- a/apps/rsa.c
+++ b/apps/rsa.c
@@ -68,6 +68,7 @@
 #include <openssl/evp.h>
 #include <openssl/x509.h>
 #include <openssl/pem.h>
+#include <openssl/bn.h>
 
 #undef PROG
 #define PROG	rsa_main

apps/speed.c

diff --git a/apps/speed.c b/apps/speed.c
index ccc074f..4008930 100644
--- a/apps/speed.c
+++ b/apps/speed.c
@@ -157,6 +157,7 @@
 #include <sys/param.h>
 #endif
 
+#include <openssl/bn.h>
 #ifndef OPENSSL_NO_DES
 #include <openssl/des.h>
 #endif

apps/version.c

diff --git a/apps/version.c b/apps/version.c
index 041da37..69ef3e1 100644
--- a/apps/version.c
+++ b/apps/version.c
@@ -115,6 +115,7 @@
 #include "apps.h"
 #include <openssl/evp.h>
 #include <openssl/crypto.h>
+#include <openssl/bn.h>
 #ifndef OPENSSL_NO_MD2
 # include <openssl/md2.h>
 #endif