libc: Remove the unused lib_libdtoa.c

__dtoa is not used because currently NuttX uses other
function called __dtoa_engine() to do the same thing

Signed-off-by: Xiang Xiao <[email protected]>

LICENSE

@@ -6094,44 +6094,6 @@ LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.
 
-libs/libc/stdio/lib_libdtoa.c
-================================
-
-Copyright (c) 1990, 1993
-     The Regents of the University of California.  All rights reserved.
-
-This code is derived from software contributed to Berkeley by
-Chris Torek.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions
-are met:
-
-1. Redistributions of source code must retain the above copyright
-   notice, this list of conditions and the following disclaimer.
-2. Redistributions in binary form must reproduce the above copyright
-   notice, this list of conditions and the following disclaimer in the
-   documentation and/or other materials provided with the distribution.
-3. All advertising materials mentioning features or use of this software
-   must display the following acknowledgement:
-     This product includes software developed by the University of
-     California, Berkeley and its contributors.
-4. Neither the name of the University nor the names of its contributors
-   may be used to endorse or promote products derived from this software
-   without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
-ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
-FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
-OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
-HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
-OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
-SUCH DAMAGE.
-
 libs/libc/stdio/lib_libvsprintf.c
 ====================================
 

libs/libc/libc.h

@@ -178,13 +178,6 @@ extern "C"
  * Public Function Prototypes
  ****************************************************************************/
 
-/* Defined in lib_dtoa.c */
-
-#ifdef CONFIG_LIBC_FLOATINGPOINT
-FAR char *__dtoa(double d, int mode, int ndigits, FAR int *decpt,
-                 FAR int *sign, FAR char **rve);
-#endif
-
 /* Defined in lib_getfullpath.c */
 
 int lib_getfullpath(int dirfd, FAR const char *path,