Fix naming scheme for configure cache variables.

In order to be cached, configure variables need to contain the
string '_cv_', and they should begin with a package-specific
prefix in order to avoid interfering with third-party macros.
Rename ld_dashr, ld_wl_rpath, ld_rpath to git_cv_ld_dashr etc.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

configure.ac

@@ -114,31 +114,31 @@ AC_MSG_NOTICE([CHECKS for programs])
 #
 AC_PROG_CC([cc gcc])
 # which switch to pass runtime path to dynamic libraries to the linker
-AC_CACHE_CHECK([if linker supports -R], ld_dashr, [
+AC_CACHE_CHECK([if linker supports -R], git_cv_ld_dashr, [
    SAVE_LDFLAGS="${LDFLAGS}"
    LDFLAGS="${SAVE_LDFLAGS} -R /"
-   AC_LINK_IFELSE(AC_LANG_PROGRAM([], []), [ld_dashr=yes], [ld_dashr=no])
+   AC_LINK_IFELSE(AC_LANG_PROGRAM([], []), [git_cv_ld_dashr=yes], [git_cv_ld_dashr=no])
    LDFLAGS="${SAVE_LDFLAGS}"
 ])
-if test "$ld_dashr" = "yes"; then
+if test "$git_cv_ld_dashr" = "yes"; then
    AC_SUBST(CC_LD_DYNPATH, [-R])
 else
-   AC_CACHE_CHECK([if linker supports -Wl,-rpath,], ld_wl_rpath, [
+   AC_CACHE_CHECK([if linker supports -Wl,-rpath,], git_cv_ld_wl_rpath, [
       SAVE_LDFLAGS="${LDFLAGS}"
       LDFLAGS="${SAVE_LDFLAGS} -Wl,-rpath,/"
-      AC_LINK_IFELSE(AC_LANG_PROGRAM([], []), [ld_wl_rpath=yes], [ld_wl_rpath=no])
+      AC_LINK_IFELSE(AC_LANG_PROGRAM([], []), [git_cv_ld_wl_rpath=yes], [git_cv_ld_wl_rpath=no])
       LDFLAGS="${SAVE_LDFLAGS}"
    ])
-   if test "$ld_wl_rpath" = "yes"; then
+   if test "$git_cv_ld_wl_rpath" = "yes"; then
       AC_SUBST(CC_LD_DYNPATH, [-Wl,-rpath,])
    else
-      AC_CACHE_CHECK([if linker supports -rpath], ld_rpath, [
+      AC_CACHE_CHECK([if linker supports -rpath], git_cv_ld_rpath, [
          SAVE_LDFLAGS="${LDFLAGS}"
          LDFLAGS="${SAVE_LDFLAGS} -rpath /"
-         AC_LINK_IFELSE(AC_LANG_PROGRAM([], []), [ld_rpath=yes], [ld_rpath=no])
+         AC_LINK_IFELSE(AC_LANG_PROGRAM([], []), [git_cv_ld_rpath=yes], [git_cv_ld_rpath=no])
          LDFLAGS="${SAVE_LDFLAGS}"
       ])
-      if test "$ld_rpath" = "yes"; then
+      if test "$git_cv_ld_rpath" = "yes"; then
          AC_SUBST(CC_LD_DYNPATH, [-rpath])
       else
          AC_MSG_WARN([linker does not support runtime path to dynamic libraries])