databases/py-mysqlclient and others fail to build after update of mariadb100-client

[Wolfgang Zenker]

Hi,

the immediate reason for the build failure appears to be a weird option
"-l-pthread" in the cc invocation:

------------------------
-- snip ---
building '_mysql' extension
creating build/temp.freebsd-11.1-RELEASE-p12-amd64-2.7
cc -DNDEBUG -O2 -pipe -DLIBICONV_PLUG -fstack-protector -fno-strict-aliasing -DLIBICONV_PLUG -fPIC -Dversion_info=(1,3,12,'final',0) -D__version__=1.3.12 -I/usr/local/include/mysql -I/usr/local/include/mysql/.. -I/usr/local/include/python2.7 -c _mysql.c -o build/temp.freebsd-11.1-RELEASE-p12-amd64-2.7/_mysql.o
cc -shared -fstack-protector -O2 -pipe -DLIBICONV_PLUG -fstack-protector -fno-strict-aliasing -DLIBICONV_PLUG build/temp.freebsd-11.1-RELEASE-p12-amd64-2.7/_mysql.o -L/usr/local/lib/mysql -L/usr/local/lib -L/usr/local/lib -lmysqlclient_r -l-pthread -lz -lm -lexecinfo -lssl -lcrypto -lpython2.7 -o build/lib.freebsd-11.1-RELEASE-p12-amd64-2.7/_mysql.so
/usr/bin/ld: cannot find -l-pthread
cc: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'cc' failed with exit status 1
*** Error code 1
------------------------

As the port itself has not changed for several weeks, the real problem
must be somewhere else, probably in the mariadb port?
Any idea where this weird lib parameter comes from and how / where to
fix it?

Wolfgang