pidgin/pidgin

Use LT_LIB_M to determine if we need to link to the math library and link Pidgin to the X11 libraries
release-2.x.y
2021-04-11, Gary Kramlich
132d17234930
Use LT_LIB_M to determine if we need to link to the math library and link Pidgin to the X11 libraries

Gentoo ran into an issue with the gold linker without -lm. The original patch
and work came from Justin Lechner. https://bugs.gentoo.org/386079

Gentoo also ran into an issue with X11_LIBS not being added to pidgin. This
should already be implicit everywhere except for homebrew which patches X11
out of their build. Original patch/work came from and. https://bugs.gentoo.org/500762

Testing Done:
Installed and ran locally.

Reviewed at https://reviews.imfreedom.org/r/608/
# Rules on how to make object files from various sources
%.o: %.c
$(CC) $(CFLAGS) $(DEFINES) $(INCLUDE_PATHS) -o $@ -c $<
%.c: %.xs
$(PERL) -MExtUtils::ParseXS -e 'ExtUtils::ParseXS::process_file(filename => "$<", output => "$@", typemap => "$(PURPLE_PERL_TOP)/common/typemap");'
%.o: %.rc
$(WINDRES) -I$(PURPLE_TOP) -i $< -o $@
%.desktop: %.desktop.in $(wildcard $(PIDGIN_TREE_TOP)/po/*.po)
LC_ALL=C $(PERL) $(INTLTOOL_MERGE) -d -u -c $(PIDGIN_TREE_TOP)/po/.intltool-merge-cache $(PIDGIN_TREE_TOP)/po $< $@