pidgin/pidgin

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/
/* This file contains macros that wrap calls to the purple dbus module.
These macros call the appropriate functions if the build includes
dbus support and do nothing otherwise. See "dbus-server.h" for
documentation. */
#ifndef _PURPLE_DBUS_MAYBE_H_
#define _PURPLE_DBUS_MAYBE_H_
#ifdef HAVE_DBUS
#ifndef DBUS_API_SUBJECT_TO_CHANGE
#define DBUS_API_SUBJECT_TO_CHANGE
#endif
#include "dbus-server.h"
/* this provides a type check */
#define PURPLE_DBUS_REGISTER_POINTER(ptr, type) { \
type *typed_ptr = ptr; \
purple_dbus_register_pointer(typed_ptr, PURPLE_DBUS_TYPE(type)); \
}
#define PURPLE_DBUS_UNREGISTER_POINTER(ptr) purple_dbus_unregister_pointer(ptr)
#else /* !HAVE_DBUS */
#define PURPLE_DBUS_REGISTER_POINTER(ptr, type) { \
if (ptr) {} \
}
#define PURPLE_DBUS_UNREGISTER_POINTER(ptr)
#define DBUS_EXPORT
#endif /* HAVE_DBUS */
#endif