crypto: drop the dangling crypto.h symlink and its last references

c912d090 ("crypto: Removed internal tomcat crypto.") deleted the
crypto/ tree but left accel-pppd/include/crypto.h behind, a tracked
symlink to ../../crypto/crypto.h which has pointed at nothing since.

backup_file.c still includes it, so it fails to compile with

  fatal error: crypto.h: No such file or directory

That goes unnoticed because accel-pppd/CMakeLists.txt has
ADD_SUBDIRECTORY(backup) commented out, i.e. backup_file.c is not part
of any build; the breakage only shows up for whoever re-enables it.
Include <openssl/md5.h> instead, which is what the file actually needs
(MD5_CTX and friends) and what c912d090 did for every file it touched.

sstp.c and radius/packet.c defer to crypto.h for the rationale behind
their OPENSSL_API_COMPAT define. Spell it out locally instead, and point
at the project wide ADD_DEFINITIONS() in the top level CMakeLists.txt
added by c1689506 ("openssl: suppress deprecated API warnings"), noting
why the local define is kept despite being redundant with it: it has to
be visible before the first OpenSSL header.

Then remove the symlink, which nothing references anymore.

4 files changed, 12 insertions, 6 deletions

diff --git a/accel-pppd/backup/backup_file.c b/accel-pppd/backup/backup_file.c
index 06dc02d4..472694f0 100644
--- a/accel-pppd/backup/backup_file.c
+++ b/accel-pppd/backup/backup_file.c
@@ -10,11 +10,12 @@
 #include <sys/uio.h>
 #include <sys/mman.h>
 
+#include <openssl/md5.h>
+
 #include "triton.h"
 #include "log.h"
 #include "ap_session.h"
 #include "backup.h"
-#include "crypto.h"
 #include "memdebug.h"
 
 #define VERSION 1
diff --git a/accel-pppd/ctrl/sstp/sstp.c b/accel-pppd/ctrl/sstp/sstp.c
index 2fd8cb35..db08ae93 100644
--- a/accel-pppd/ctrl/sstp/sstp.c
+++ b/accel-pppd/ctrl/sstp/sstp.c
@@ -21,8 +21,11 @@
 #include "linux_ppp.h"
 
 /*
- * Suppress OpenSSL 3.0 deprecation warnings for DH API.
- * See crypto.h for detailed explanation.
+ * Suppress OpenSSL 3.0 deprecation warnings for the DH API: it is deprecated
+ * but still functional, and still required for protocol compatibility. The
+ * project sets this for every target (see the top level CMakeLists.txt); it
+ * is repeated here because it only takes effect if it is defined before the
+ * first OpenSSL header is pulled in.
  */
 #define OPENSSL_API_COMPAT 0x10100000L
 #include <openssl/ssl.h>
diff --git a/accel-pppd/include/crypto.h b/accel-pppd/include/crypto.h
deleted file mode 120000
index 2f3f63cb..00000000
--- a/accel-pppd/include/crypto.h
+++ /dev/null
@@ -1 +0,0 @@
-../../crypto/crypto.h
\ No newline at end of file
diff --git a/accel-pppd/radius/packet.c b/accel-pppd/radius/packet.c
index cfc0bc29..c7e91349 100644
--- a/accel-pppd/radius/packet.c
+++ b/accel-pppd/radius/packet.c
@@ -10,8 +10,11 @@
 #include <arpa/inet.h>
 
 /*
- * Suppress OpenSSL 3.0 deprecation warnings for HMAC API.
- * See crypto.h for detailed explanation.
+ * Suppress OpenSSL 3.0 deprecation warnings for the HMAC API: it is
+ * deprecated but still functional, and still required for protocol
+ * compatibility. The project sets this for every target (see the top level
+ * CMakeLists.txt); it is repeated here because it only takes effect if it is
+ * defined before the first OpenSSL header is pulled in.
  */
 #define OPENSSL_API_COMPAT 0x10100000L
 #include <openssl/hmac.h>