textproc/augeas: fix build with clang 15

During an exp-run for llvm 15 (see bug 265425), it turned out that
textproc/augeas failed to build with clang 15:

  internal.c:436:12: error: incompatible integer to pointer conversion returning 'int' from a function with result type 'const char *' [-Wint-conversion]
      return strerror_r(errnum, buf, len);
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
  1 error generated.

This is because the GNU variant of strerror_r() is erroneously chosen.
Use the BSD variant instead.

PR:		268231
Approved by:	romain (maintainer)
MFH:		2022Q4

textproc/augeas/files/patch-src_internal.c

@@ -0,0 +1,11 @@
+--- src/internal.c.orig	2018-08-10 20:17:35 UTC
++++ src/internal.c
+@@ -431,7 +431,7 @@ const char *xstrerror(int errnum, char *buf, size_t le
+
+ const char *xstrerror(int errnum, char *buf, size_t len) {
+ #ifdef HAVE_STRERROR_R
+-# ifdef __USE_GNU
++# if defined(__USE_GNU) && defined(__GLIBC__)
+     /* Annoying linux specific API contract */
+     return strerror_r(errnum, buf, len);
+ # else