Make sure that strerror-override.c compiles, no matter what.

Patch from Dima Pasechnik.

This fixes build on Solaris (and would also on Cygwin -- but we have
already worked around that in a different way).

Author: mkoeppe

code/gnulib/strerror-override.c

@@ -31,6 +31,7 @@
 
 /* If ERRNUM maps to an errno value defined by gnulib, return a string
    describing the error.  Otherwise return NULL.  */
+#ifndef strerror_override_switch
 const char *
 strerror_override (int errnum)
 {
@@ -300,3 +301,4 @@ strerror_override (int errnum)
       return NULL;
     }
 }
+#endif

code/gnulib/strerror-override.h

@@ -51,6 +51,7 @@
 extern const char *strerror_override (int errnum);
 # else
 #  define strerror_override(ignored) NULL
+#  define strerror_override_switch
 # endif
 
 #endif /* _GL_STRERROR_OVERRIDE_H */

install-reloc

@@ -148,13 +148,15 @@ fi
 # Compile wrapper.
 #
 # CHANGE: We added source files lstat, stat here to get it compile on
-# Mac OS X.  But this is all very brittle; for example on Cygwin,
-# strerror-override.c does not compile (it is excluded when compiling
-# libgnu.a, but here it is included conditionally.)  May be better to
-# link against the built gnulib, but this is tricky because of
-# possible libtool.  So we are leaving it like this for now, and on
+# Mac OS X.  But this is all very brittle; for example on Cygwin and
+# Solaris, strerror-override.c does not compile (it is excluded when
+# compiling libgnu.a, but here it is included conditionally.)  May be
+# better to link against the built gnulib, but this is tricky because
+# of possible libtool.  So we are leaving it like this for now, and on
 # Cygwin disable compilation of wrappers, because everything seems to
-# work fine without them?! --mkoeppe, 2013-08-14.
+# work fine without them?!  To also get it to work on Solaris, used
+# patch from Dima Pasechnik to make strerror-override.c compile.
+# --mkoeppe, 2013-08-20.
 func_verbose $compile_command \
              -I"$builddir" -I"$srcdir" -I"$config_h_dir" \
              -DHAVE_CONFIG_H -DIN_RELOCWRAPPER -DNO_XMALLOC \