libosmocore: system-talloc+bundled-talloc support

[Jan Engelhardt]

"--disable-talloc" had the effect of a "--enable-system-talloc".
So the first patch fixes up all the link failures by adding -ltalloc
where needed, _for the case that one decides to use disable-talloc_.

Second patch will use pkg-config to determine the parameters for
a system talloc. These will be used unconditionally, because the
variables TALLOC_CFLAGS/TALLOC_LIBS will be empty when using the
bundled talloc.

===
The following changes since commit c60de4f35f3f73f3d79b4ff61d0a20b92f818702:

build: fix linker error with kasumi_test (2014-10-03 08:48:31 +0200)

are available in the git repository at:

git://git.inai.de/libosmocore HEAD

for you to fetch changes up to d6c1607a724a07416c7d39f9b43f7af7349de666:

build: default to system-provided talloc (2014-10-03 12:43:25 +0200)

----------------------------------------------------------------
Jan Engelhardt (3):
build: resolve link failure in libosmogsm when --disable-talloc is used
build: allow using a system-provided talloc properly
build: default to system-provided talloc

.gitignore | 1 +
configure.ac | 26 +++++++++++++++++++------
include/Makefile.am | 5 +++--
include/osmocom/core/talloc.h.in | 6 ++++++
include/osmocom/core/{talloc.h => talloc_int.h} | 0
src/Makefile.am | 7 ++++---
src/gsm/Makefile.am | 5 +++--
tests/Makefile.am | 12 ++++++------
tests/msgfile/msgfile_test.c | 1 +
9 files changed, 44 insertions(+), 19 deletions(-)
create mode 100644 include/osmocom/core/talloc.h.in
rename include/osmocom/core/{talloc.h => talloc_int.h} (100%)