libpcre2-posix uses the same name as POSIX

[Malaise]

At present the POSIX interface of the (new) PCRE2 defines the same names as the standard POSIX regex API, e.g. "extern int regcomp(regex_t *, const char *, int);"
On Debian, despite including pcre2posix.h and linking with libpcre2-posix, the program will likely bind to the libc entry with the same name.

See attached source:
gcc -pipe -fPIC -std=gnu99 -D_FILE_OFFSET_BITS=64 -pthpcre2-posixread -c tpcre2.c -o tpcre2.o
gcc -o tpcre2 tpcre2.o -lpcre2-posix -lpcre2-8 -lpthread -lm
ldd tpcre2
 linux-vdso.so.1 => (0x00007ffd0dbb7000)
 libpcre2-8.so.0 => /usr/lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x00007f7ee2fd6000)
 libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f7ee2c0d000)
 libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f7ee29ef000)
 /lib64/ld-linux-x86-64.so.2 (0x0000558e24854000)

According to a discussion in the PCRE forum (https://bugs.exim.org/show_bug.cgi?id=1830), the development team will not change these names because of risk of regression, because it has always been like that, because it works when PCRE2 is installed in a custom prefix (e.g. /usr/local)...

NOTE:
On the (previous) PCRE POSIX API, a patch (https://sources.debian.net/src/pcre3/2:8.38-3.1/debian/patches/pcreposix.patch/) ensures that including pcreposix.h will lead to bind with libpcreposix.
This patch is to define specific names (e.g. pcreposix_regcomp (...)) and #define the standard name as an "alias" to it (#define regcomp pcreposix_regcomp).

This patch works fine and may probably be reproduced in pcre2-posix.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: libpcre2-posix0 10.21-1
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: XFCE
Date: Sun May 29 14:19:47 2016
Dependencies:
 gcc-6-base 6.0.1-0ubuntu1
 libc6 2.23-0ubuntu3
 libgcc1 1:6.0.1-0ubuntu1
 libpcre2-8-0 10.21-1
InstallationDate: Installed on 2016-02-01 (117 days ago)
InstallationMedia: Xubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
SourcePackage: pcre2
UpgradeStatus: Upgraded to xenial on 2016-04-23 (36 days ago)