Fix overlining issues

https://wiki.openmandriva.org/en/Overlinking_issues_in_packaging

I provided extensive explanation on the upstream:
https://jira.mariadb.org/browse/CONC-410

--- mariadb-connector-c-3.0.10-src/mariadb_config/libmariadb.pc.in	2019-05-04 07:04:14.000000000 -0400
+++ mariadb-connector-c-3.0.10-src/mariadb_config/libmariadb.pc.in_patched	2019-05-21 08:25:09.825206424 -0400
@@ -14,6 +14,7 @@ Name: libmariadb
 Version: @CPACK_PACKAGE_VERSION@
 Description: MariaDB Connector/C dynamic library
 Cflags: -I${includedir}
-Libs: -L${libdir} -lmariadb @extra_dynamic_LDFLAGS@
+Libs: -L${libdir} -lmariadb
+Libs.private: @extra_dynamic_LDFLAGS@
 
 
--- mariadb-connector-c-3.0.10-src/mariadb_config/mariadb_config.c.in	2019-05-04 07:04:14.000000000 -0400
+++ mariadb-connector-c-3.0.10-src/mariadb_config/mariadb_config.c.in_patched	2019-05-21 08:46:08.473206424 -0400
@@ -6,7 +6,7 @@
 static char *mariadb_progname;
 
 #define INCLUDE "-I@CMAKE_INSTALL_PREFIX@/@INSTALL_INCLUDEDIR@ -I@CMAKE_INSTALL_PREFIX@/@INSTALL_INCLUDEDIR@/mysql"
-#define LIBS    "-L@CMAKE_INSTALL_PREFIX@/@INSTALL_LIBDIR@/ -lmariadb @extra_dynamic_LDFLAGS@"
+#define LIBS    "-L@CMAKE_INSTALL_PREFIX@/@INSTALL_LIBDIR@/ -lmariadb"
 #define LIBS_SYS "@extra_dynamic_LDFLAGS@"
 #define CFLAGS  INCLUDE
 #define VERSION "@MARIADB_CLIENT_VERSION@"