patch 7.4.750 Problem: Cannot build with clang 3.5 on Cygwin with perl enabled. Solution: Strip "-fdebug-prefix-map" in configure. (Ken Takata)

Author: brammool

src/configure.in

@@ -957,8 +957,10 @@ if test "$enable_perlinterp" = "yes" -o "$enable_perlinterp" = "dynamic"; then
       done
       AC_SUBST(vi_cv_perlsitelib)
       dnl Remove "-fno-something", it breaks using cproto.
+      dnl Remove "-fdebug-prefix-map", it isn't supported by clang.
       perlcppflags=`$vi_cv_path_perl -Mlib=$srcdir -MExtUtils::Embed \
-	      -e 'ccflags;perl_inc;print"\n"' | sed -e 's/-fno[[^ ]]*//'`
+	      -e 'ccflags;perl_inc;print"\n"' | sed -e 's/-fno[[^ ]]*//' \
+			-e 's/-fdebug-prefix-map[[^ ]]*//g'`
       dnl Remove "-lc", it breaks on FreeBSD when using "-pthread".
       perllibs=`cd $srcdir; $vi_cv_path_perl -MExtUtils::Embed -e 'ldopts' | \
 		sed -e '/Warning/d' -e '/Note (probably harmless)/d' \