Improve debug capabilities when using bash

When calling the _debug3() function will print the filename, function
name, and line number when running under bash

acme.sh

@@ -265,6 +265,37 @@ _usage() {
   printf "\n" >&2
 }
 
+__debug_bash_helper() {
+  # At this point only do for --debug 3
+  if [ "${DEBUG:-$DEBUG_LEVEL_NONE}" -lt "$DEBUG_LEVEL_3" ]; then
+    echo ""
+    return
+  fi
+  # Return extra debug info when running with bash, otherwise return empty
+  # string.
+  if [ -z "${BASH_VERSION}" ]; then
+    echo ""
+    return
+  fi
+  # We are a bash shell at this point, return the filename, function name, and
+  # line number as a string
+  _dbh_saveIFS=$IFS
+  IFS=" "
+  # Must use eval or syntax error happens under dash
+  # Use 'caller 1' as we want one level up the stack as we should be called
+  # by one of the _debug* functions
+  eval "_dbh_called=($(caller 1))"
+  IFS=$_dbh_saveIFS
+  _dbh_file=${_dbh_called[2]}
+  if [ -n "${_script_home}" ]; then
+    # Trim off the _script_home directory name
+    _dbh_file=${_dbh_file#$_script_home/}
+  fi
+  _dbh_function=${_dbh_called[1]}
+  _dbh_lineno=${_dbh_called[0]}
+  printf "%-40s " "$_dbh_file:${_dbh_function}:${_dbh_lineno}"
+}
+
 _debug() {
   if [ "${LOG_LEVEL:-$DEFAULT_LOG_LEVEL}" -ge "$LOG_LEVEL_1" ]; then
     _log "$@"
@@ -273,7 +304,8 @@ _debug() {
     _syslog "$SYSLOG_DEBUG" "$@"
   fi
   if [ "${DEBUG:-$DEBUG_LEVEL_NONE}" -ge "$DEBUG_LEVEL_1" ]; then
-    _printargs "$@" >&2
+    _bash_debug=$(__debug_bash_helper)
+    _printargs "${_bash_debug}$@" >&2
   fi
 }
 
@@ -306,7 +338,8 @@ _debug2() {
     _syslog "$SYSLOG_DEBUG" "$@"
   fi
   if [ "${DEBUG:-$DEBUG_LEVEL_NONE}" -ge "$DEBUG_LEVEL_2" ]; then
-    _printargs "$@" >&2
+    _bash_debug=$(__debug_bash_helper)
+    _printargs "${_bash_debug}$@" >&2
   fi
 }
 
@@ -338,7 +371,8 @@ _debug3() {
     _syslog "$SYSLOG_DEBUG" "$@"
   fi
   if [ "${DEBUG:-$DEBUG_LEVEL_NONE}" -ge "$DEBUG_LEVEL_3" ]; then
-    _printargs "$@" >&2
+    _bash_debug=$(__debug_bash_helper)
+    _printargs "${_bash_debug}$@" >&2
   fi
 }