configure: Support libsctp < 1.0.17 without libsctp.pc
libsctp 1.0.17 is the first to contain a pkgconfig file in upstream.
Current OpenSure Leap 15.3 as well as our OpenEmbedded meta-telephony
layer still ship 1.0.16 which contain no pkgconfig file.
Let's attempt first finding the .pc file, and otherwise manually link
against the lib.
Related: https://bugzilla.opensuse.org/show_bug.cgi?id=1197590
Related: https://build.opensuse.org/request/show/965348
Fixes: 12eed19066a11aece6f346b54b85326bc6ba7f0b
Change-Id: I241634388c2d32adffebd860c88bdd13002a6af0
diff --git a/libosmocore.pc.in b/libosmocore.pc.in
index 6296417..d804b8e 100644
--- a/libosmocore.pc.in
+++ b/libosmocore.pc.in
@@ -7,7 +7,7 @@
Description: C Utility Library
Version: @VERSION@
Requires: talloc
-Requires.private: libsctp
+Requires.private: @LIBSCTP_PC@
Libs: -L${libdir} -losmocore
-Libs.private: @PTHREAD_LIBS@
+Libs.private: @PTHREAD_LIBS@ @LIBSCTP_LIBS@
Cflags: -I${includedir}/ @PTHREAD_CFLAGS@