AVR: Update weblinks to AVR-LibC.

AVR-LibC has moved to GitHub, adjust web links:
https://github.com/avrdudes/avr-libc (project)
https://avrdudes.github.io/avr-libc/avr-libc-user-manual (wwwdocs)

gcc/
	* doc/invoke.texi (AVR Options): Update AVR-LibC weblink from
	nongnu.org to https://github.com/avrdudes/avr-libc
	* doc/extend.texi (AVR Named Address Spaces): Same.
	(AVR Function Attributes): Same.
	* doc/install.texi (Cross-Compiler-Specific Options, AVR): Same.

3 files changed, 8 insertions, 7 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 2d795ba..c95df84 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -1593,7 +1593,7 @@ locates data in flash but
 accesses to these data read from generic address space, i.e.@:
 from RAM,
 so that you need special accessors like @code{pgm_read_byte}
-from @w{@uref{https://www.nongnu.org/avr-libc/user-manual/,AVR-LibC}}
+from @w{@uref{https://avrdudes.github.io/avr-libc/avr-libc-user-manual/,AVR-LibC}}
 together with attribute @code{progmem}.
 
 @noindent
@@ -5181,7 +5181,7 @@ globally enable interrupts.
 
 The recommended way to use these attributes is by means of the
 @code{ISR} macro provided by @code{avr/interrupt.h} from
-@w{@uref{https://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html,,AVR-LibC}}:
+@w{@uref{https://avrdudes.github.io/avr-libc/avr-libc-user-manual/group__avr__interrupts.html,,AVR-LibC}}:
 @example
 #include <avr/interrupt.h>
 
@@ -5219,7 +5219,7 @@ static void my_handler (void)
 Notice that the handler function needs not to be externally visible.
 The recommended way to use these attributes is by means of the
 @code{ISR_N} macro provided by @code{avr/interrupt.h} from
-@w{@uref{https://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html,,AVR-LibC}}:
+@w{@uref{https://avrdudes.github.io/avr-libc/avr-libc-user-manual/group__avr__interrupts.html,,AVR-LibC}}:
 
 @example
 #include <avr/interrupt.h>
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 62a6110..1ca0f14 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -2688,8 +2688,9 @@ omitted from @file{libgcc.a} on the assumption that it will be provided by
 <a name="avr"></a>
 @end html
 @item --with-avrlibc
-Only supported for the AVR target. Specifies that @samp{AVR-Libc} is
-being used as the target C@tie{} library.  This causes float support
+Only supported for the AVR target. Specifies that
+@uref{https://github.com/avrdudes/avr-libc/,,AVR-LibC}
+is being used as the target C@tie{} library.  This causes float support
 functions like @code{__addsf3} to be omitted from @file{libgcc.a} on
 the assumption that it will be provided by @file{libm.a}.  For more
 technical details, cf. @uref{https://gcc.gnu.org/PR54461,,PR54461}.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index a6cd511..511b8c8 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -24053,7 +24053,7 @@ a device library @code{lib@var{mcu}.a} and a
 @uref{https://gcc.gnu.org/wiki/avr-gcc#spec-files,device-specs} file
 @code{specs-@var{mcu}}. Only the latter is provided by the compiler
 according the supported @code{@var{mcu}}s below.  The rest is supported
-by @w{@uref{https://www.nongnu.org/avr-libc/,AVR-LibC}}, or by means of
+by @w{@uref{https://github.com/avrdudes/avr-libc/,AVR-LibC}}, or by means of
 @uref{https://gcc.gnu.org/wiki/avr-gcc#atpack,@code{atpack}} files
 from the hardware manufacturer.
 
@@ -24289,7 +24289,7 @@ points to.
 The startup code from libgcc never sets @code{EIND}.
 Notice that startup code is a blend of code from libgcc and AVR-LibC.
 For the impact of AVR-LibC on @code{EIND}, see the
-@w{@uref{https://www.nongnu.org/avr-libc/user-manual/,AVR-LibC user manual}}.
+@w{@uref{https://avrdudes.github.io/avr-libc/avr-libc-user-manual/,AVR-LibC user manual}}.
 
 @item
 It is legitimate for user-specific startup code to set up @code{EIND}