[PATCH] Makefile: remove the NO_R_TO_GCC_LINKER flag

Remove the NO_R_TO_GCC_LINKER flag, thus switching the default to "-Wl,-rpath,$LIBPATH" instead of our current "-R$LIBPATH". This is a relatively obscure thing that only kicks in when using one of the LIBDIR flags, e.g. LIBPCREDIR or CURLDIR.

How we invoke the linker to do this can still be overridden with CC_LD_DYNPATH, as seen in our configure.ac script.

Our use of "-R" dates back to 455a7f3275 ("More portability.", 2005-09-30). Soon after that in bbfc63dd78 ("gcc does not necessarily pass runtime libpath with -R", 2006-12-27) the NO_R_TO_GCC flag was added, allowing optional use of "-Wl,-rpath=".

Then in f5b904db6b ("Makefile: Allow CC_LD_DYNPATH to be overriden", 2008-08-16) the ability to override this flag to something else entirely was added, as some linkers use neither "-Wl,-rpath," nor "-R".

From what I can tell we should, with the benefit of hindsight, have made this change back in 2006. GCC & ld supported this type of invocation back then, or since at least binutils-gdb.git's[1] a1ad915dc4 ("[...]Add support for -rpath[...]", 1994-07-20). Most people compiling git with a custom LIBDIR are going to be on a GNU-ish system, and having to provide this NO_R_TO_GCC_LINKER flag on top of a custom LIBDIR is annoying.

There are some OS's that don't support -rpath, e.g. AIX ld just supports "-R". Perhaps we should follow this up with some config.mak.uname changes, but as noted it's quite possible that nobody on these platforms uses this (instead libraries in the system's search path). We *could* also use "-Wl,-R", but let's not introduce something new.

Further reading and prior art can be found at [2][3][4][5]. Making a plain "-R" an error seems from reading those reports to have been introduced in GCC 4.6 released on March 25, 2011, but I couldn't confirm this with absolute certainty, its release notes are ambiguous on the subject, and I couldn't be bothered to try to build & bisect it against GCC 4.5.

1. git://sourceware.org/git/binutils-gdb.git
2. https://github.com/tsuna/boost.m4/issues/15
3. https://bugzilla.gnome.org/show_bug.cgi?id=641416
4. https://stackoverflow.com/questions/12629042/g-4-6-real-error-unrecognized-option-r
5. https://curl.haxx.se/mail/archive-2014-11/0005.html
6. https://gcc.gnu.org/gcc-4.6/changes.html

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
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Looking at that HP/UX configure patch I was reminded of being annoyed by the NO_R_TO_GCC_LINKER flag.

 Makefile | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)