configure: don't check ./revision, it never exists

Stop checking the ./revision file for the git revision info, its never
created.

configure.ac

@@ -2510,11 +2510,7 @@ return 0;
 
     AM_CONDITIONAL([HAS_FUZZLDFLAGS], [test "x$has_sanitizefuzzer" = "xyes"])
 
-# get revision
-    if test -f ./revision; then
-        REVISION=`cat ./revision`
-        AC_DEFINE_UNQUOTED([REVISION],[${REVISION}],[Git revision])
-    else
+# get git revision and last commit date
     AC_PATH_PROG(HAVE_GIT_CMD, git, "no")
     if test "$HAVE_GIT_CMD" != "no"; then
         if [ test -d .git ]; then
@@ -2524,7 +2520,6 @@ return 0;
             AC_DEFINE_UNQUOTED([REVISION],[${REVISION}],[Git revision])
         fi
     fi
-    fi
 
 # get MAJOR_MINOR version for embedding in configuration file.
     MAJOR_MINOR=`expr "${PACKAGE_VERSION}" : "\([[0-9]]\+\.[[0-9]]\+\).*"`