Expand OPENSSL_SHLIB_VERSION correctly.

Fixes: e5ba78da08e0bf0b1603352b380760ae15358c47 ("Fix build on OpenSSL 3")

src/common.h

@@ -100,8 +100,11 @@
 #define unlikely(x)  (x)
 #endif
 
-#ifndef STRINGIFY
-#define STRINGIFY(x) #x
+#ifndef __STRING
+#define __STRING(x)     #x              /* stringify without expanding x */
+#endif
+#ifndef __XSTRING
+#define __XSTRING(x)    __STRING(x)     /* expand x, then stringify */
 #endif
 
 #define lengthof(x) (sizeof(x)/sizeof(x[0]))

src/libcrypto.cc

@@ -37,7 +37,7 @@
 #ifndef OPENSSL_SHLIB_VERSION
 #define OPENSSL_SHLIB_VERSION_STR SHLIB_VERSION_NUMBER
 #else
-#define OPENSSL_SHLIB_VERSION_STR STRINGIFY(OPENSSL_SHLIB_VERSION)
+#define OPENSSL_SHLIB_VERSION_STR __XSTRING(OPENSSL_SHLIB_VERSION)
 #endif
 
 void *libcrypto_handle = NULL;

src/libssl.cc

@@ -37,7 +37,7 @@
 #ifndef OPENSSL_SHLIB_VERSION
 #define OPENSSL_SHLIB_VERSION_STR SHLIB_VERSION_NUMBER
 #else
-#define OPENSSL_SHLIB_VERSION_STR STRINGIFY(OPENSSL_SHLIB_VERSION)
+#define OPENSSL_SHLIB_VERSION_STR __XSTRING(OPENSSL_SHLIB_VERSION)
 #endif
 
 void *libssl_handle = NULL;