perl: update to 5.26.1

Required changes:

* Add qualifying '.' to scripts or to @INC, as appropriate since we're
  enabling default_inc_excludes_dot;

* Add new platform/library definitions like double-double format and
  locale library functions/headers;

* Delete patch 020 as it's been upstreamed;

Optional changes:

* Instead of using -@rm and having that fail, emit an error message,
  and be ignored, just use @rm -f instead which will always succeed.

Security
[CVE-2017-12837] Heap buffer overflow in regular expression compiler

Compiling certain regular expression patterns with the case-insensitive
modifier could cause a heap buffer overflow and crash perl. This has
now been fixed. [perl #131582]

[CVE-2017-12883] Buffer over-read in regular expression parser

For certain types of syntax error in a regular expression pattern, the
error message could either contain the contents of a random, possibly
large, chunk of memory, or could crash perl. This has now been fixed.
[perl #131598]

[CVE-2017-12814] $ENV{$key} stack buffer overflow on Windows

A possible stack buffer overflow in the %ENV code on Windows has been
fixed by removing the buffer completely since it was superfluous anyway.
[perl #131665]

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>

lang/perl/files/i486.config

@@ -6,6 +6,9 @@ ccsymbols=''
 cppccsymbols=''
 cppsymbols='__ELF__=1 _FILE_OFFSET_BITS=64 __GLIBC__=2 __GLIBC_MINOR__=2 __GNUC__=3 __GNUC_MINOR__=4 __GNU_LIBRARY__=6 _LARGEFILE_SOURCE=1 _POSIX_C_SOURCE=199506L _POSIX_SOURCE=1 __STDC__=1 __USE_BSD=1 __USE_FILE_OFFSET64=1 __USE_LARGEFILE=1 __USE_MISC=1 __USE_POSIX=1 __USE_POSIX199309=1 __USE_POSIX199506=1 __USE_POSIX2=1 __USE_SVID=1 i386=1 __i386=1 __i386__=1 linux=1 __linux=1 __linux__=1 unix=1 __unix=1 __unix__=1'
 d_casti32='undef'
+d_double_style_ieee='define'
+d_long_double_style_ieee='define'
+d_long_double_style_ieee_extended='define'
 d_modflproto='define'
 doublekind='3'
 fpossize='20'