external/coinmp: Avoid -Werror,-Wc++2b-extensions

> ClpSimplex.cpp:6038:2: error: use of a '#elifdef' directive is a C++2b extension [-Werror,-Wc++2b-extensions]
> #elifdef COIN_HAS_MUMPS
>  ^

seen with Clang 15 trunk since
<a1545f51a9>
"Warn if using `elifdef` & `elifndef` in not C2x & C++2b mode" (and which is
turned into an error because External_coinmp builds with --pedantic-errors)

Change-Id: I1db213aec91bc17c720fd58270eab452b2e4e0f5
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/134478
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

external/coinmp/UnpackedTarball_coinmp.mk

@@ -46,6 +46,7 @@ $(eval $(call gb_UnpackedTarball_add_patches,coinmp,\
 	external/coinmp/Wnon-c-typedef-for-linkage.patch \
 	external/coinmp/register.patch \
 	external/coinmp/configure-exit.patch \
+	external/coinmp/pedantic-errors.patch \
 ))
 
 # vim: set noet sw=4 ts=4:

external/coinmp/pedantic-errors.patch

@@ -0,0 +1,11 @@
+--- Clp/src/ClpSimplex.cpp
++++ Clp/src/ClpSimplex.cpp
+@@ -6035,7 +6035,7 @@
+      assert (!doKKT);
+      ClpCholeskyTaucs * cholesky = new ClpCholeskyTaucs();
+      barrier.setCholesky(cholesky);
+-#elifdef COIN_HAS_MUMPS
++#elif defined COIN_HAS_MUMPS
+      if (!doKKT) {
+           ClpCholeskyMumps * cholesky = new ClpCholeskyMumps();
+           barrier.setCholesky(cholesky);