journal: add catalog message for missing dlopen dep

catalog/systemd.catalog.in

@@ -1024,3 +1024,16 @@ Support: %SUPPORT_URL%
 The Trusted Platform Module's (TPM) NV index support is too limited to properly
 implement NV index backed additional PCRs. NvPCRs will not be allocated or
 initialized, and will not be available on the system.
+
+-- eac6d394c925493deac2ba99f3c2bb11
+Subject: An optional dependency for @FEATURE@ is not installed
+Defined-By: systemd
+Support: %SUPPORT_URL%
+
+The @FEATURE@ feature that was requested depends on an optional component that
+is loaded at runtime (for example a shared library opened via dlopen(3)), but
+that component is not installed on this system.
+
+As a result @FEATURE@ is unavailable, and is either skipped, disabled, or
+degraded to a fallback mode. Refer to the accompanying log message for the
+specific dependency that is missing, then install it to enable @FEATURE@.

src/systemd/sd-messages.h

@@ -312,6 +312,9 @@ _SD_BEGIN_DECLARATIONS;
 #define SD_MESSAGE_TPM_NVPCR_UNSUPPORTED              SD_ID128_MAKE(8f,07,a5,b8,14,ca,47,62,b8,9f,cc,30,82,e4,8a,ed)
 #define SD_MESSAGE_TPM_NVPCR_UNSUPPORTED_STR          SD_ID128_MAKE_STR(8f,07,a5,b8,14,ca,47,62,b8,9f,cc,30,82,e4,8a,ed)
 
+#define SD_MESSAGE_MISSING_DEPENDENCY                 SD_ID128_MAKE(ea,c6,d3,94,c9,25,49,3d,ea,c2,ba,99,f3,c2,bb,11)
+#define SD_MESSAGE_MISSING_DEPENDENCY_STR             SD_ID128_MAKE_STR(ea,c6,d3,94,c9,25,49,3d,ea,c2,ba,99,f3,c2,bb,11)
+
 _SD_END_DECLARATIONS;
 
 #endif