housekeeping: Remove the warning about GTimeVal is deprecated

[rbuj]

Test

$ gsettings get org.mate.thumbnail-cache maximum-age
180
$ gsettings set org.mate.thumbnail-cache maximum-age 1
$ find ~/.cache/thumbnails -type f -name *.png -exec touch -d "-1 day" {} +

CPU profiling:

diff --git a/configure.ac b/configure.ac
index d4028cd..b4f3e45 100644
--- a/configure.ac
+++ b/configure.ac
@@ -401,7 +401,7 @@ AC_ARG_ENABLE(more-warnings,
 AC_MSG_CHECKING(for more warnings)
 if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
         AC_MSG_RESULT(yes)
-        CFLAGS="\
+        CFLAGS="-lprofiler \
         -Wall \
         -Wchar-subscripts -Wmissing-declarations -Wmissing-prototypes \
         -Wnested-externs -Wpointer-arith \

# Build & run
CFLAGS="-lprofiler" LDFLAGS="-lprofiler" ./autogen.sh --prefix=/usr --enable-more-warnings && make V=1 && sudo make install
CPUPROFILE=/tmp/profile /usr/libexec/mate-settings-daemon --replace

# Force thumbnail-cache purge
gsettings set org.mate.thumbnail-cache maximum-age -1 
find ~/.cache/thumbnails -type f -name *.png -exec touch -d "-1 day" {} +
gsettings set org.mate.thumbnail-cache maximum-age 1
(wait 2 min and check ~/.cache/thumbnails/normal is empty)

# Stop profiling
/usr/libexec/mate-settings-daemon --replace

# Show output
pprof --pdf --focus=purge_thumbnail_cache /usr/libexec/mate-settings-daemon /tmp/profile > out.pdf
pprof --svg --focus=purge_thumbnail_cache /usr/libexec/mate-settings-daemon /tmp/profile > out.svg

Before

After

[raveit65]

No problems with this PR after testing it several weeks.