Fix static build.

If you want to link against the static library you have to define
LIBSSH_STATIC and link against ssh_static.

gcc -static -DLIBSSH_STATIC -lssh_static foo.c -o foo

include/libssh/libssh.h

@@ -22,8 +22,11 @@
 #ifndef _LIBSSH_H
 #define _LIBSSH_H
 
+#ifdef LIBSSH_STATIC
+  #define LIBSSH_API
+#else
   #if defined _WIN32 || defined __CYGWIN__
-  #ifdef SSH_EXPORTS
+    #ifdef LIBSSH_EXPORTS
       #ifdef __GNUC__
         #define LIBSSH_API __attribute__((dllexport))
       #else
@@ -43,6 +46,7 @@
       #define LIBSSH_API
     #endif
   #endif
+#endif
 
 #ifdef _MSC_VER
   /* Visual Studio hasn't inttypes.h so it doesn't know uint32_t */

libssh/CMakeLists.txt

@@ -156,10 +156,8 @@ set_target_properties(
         ${LIBRARY_SOVERSION}
       OUTPUT_NAME
         ssh
-      CLEAN_DIRECT_OUTPUT
-        1
       DEFINE_SYMBOL
-        SSH_EXPORTS
+        LIBSSH_EXPORTS
       COMPILE_FLAGS
         ${LIBSSH_SHARED_CFLAGS}
 )
@@ -183,10 +181,8 @@ if (WITH_STATIC_LIB)
           ${LIBRARY_VERSION}
         SOVERSION
           ${LIBRARY_SOVERSION}
-        OUTPUT_NAME
-          ssh
-        CLEAN_DIRECT_OUTPUT
-          1
+        COMPILE_FLAGS
+          "-DLIBSSH_STATIC"
   )
 
   install(