re PR target/54461 ([avr] add configure option for better AVR-Libc integration)

re PR target/54461 ([avr] add configure option for better AVR-Libc integration)

	PR target/54461
	* configure.ac (noconfigdirs,target=avr-*-*): Add target-newlib,
	target-libgloss if not configured --with-avrlibc=no.
	* configure: Regenerate.

libgcc/
	PR target/54461
	* config.host (tmake_file,host=avr-*-*): Add avr/t-avrlibc if
	not configured --with-avrlibc=no.
	* config/avr/t-avrlibc: New file.
	* Makefile.in (FPBIT_FUNCS): filter-out LIB2FUNCS_EXCLUDE.
	(DPBIT_FUNCS): Ditto.
	(TPBIT_FUNCS): Ditto.

gcc/
	PR target/54461
	* config.gcc (tm_file,target=avr-*-*): Add avr/avrlibc.h if
	not configured --with-avrlibc=no.
	(tm_defines,target=avr-*-*): Add WITH_AVRLIBC if not configured
	--with-avrlibc=no.
	* config/avr/avrlibc.h: New file.
	* config/avr/avr-c.c: Build-in define __WITH_AVRLIBC__ if
	not configured --with-avrlibc=no.
	* doc/invoke.texi (AVR Built-in Macros): Document __WITH_AVRLIBC__

From-SVN: r190967