src/filter_chain.c: Fixed typos in error messages

Signed-off-by: Florian Forster <octo@collectd.org>
configure.in: Fix quoting of AC_LANG_PROGRAM().

Autoconf 2.68 complains about that and aborts building the configure
script. *sigh*
mysql plugin: Call mysql_init() only once.

Apparently, if you call it with a structure allocated by mysql_init()
itself, it leaks memory. Thanks to Yves Mettier for pointing this out!

Fixes Github issue #274.
Allow parsing plugin_instance in parse_option().

isalnum() is not enough to catch the underscore.

Signed-off-by: Florian Forster <octo@collectd.org>
thermal plugin: fixed value submitting

Signed-off-by: Markus Knetschke <markus.knetschke@gmail.com>
Signed-off-by: Florian Forster <octo@collectd.org>
thermal plugin: set the hostname

Signed-off-by: Markus Knetschke <markus.knetschke@gmail.com>
Signed-off-by: Florian Forster <octo@collectd.org>
Don't clobber TMPDIR during Java detection

- Java detection used TMPDIR as var to parse command output
- TMPDIR is used in libltdl later on in ./configure
- alternative fix is local var or subshell
- fixes issue introduced via #33163ee

Conflicts:
	configure.in

Signed-off-by: Florian Forster <octo@collectd.org>
network plugin: Make sure gcrypt is initialized before using any of its functions.

@marekbecka found that sockent_open() is called during the configuration
phase, but gcrypt is initialized later, during the initialization phase.
This patch will initialize gcrypt in sockent_open() if any sockets with
security are configured.

Fixes Github issue #273.
Merge branch 'collectd-4.10' into collectd-5.1

Conflicts:
	configure.in
	src/mysql.c
	src/network.c
	src/thermal.c