Problem: some systems can't find pcre.h

Solution: help by pre-populating a CPPFLAGS value

Signed-off-by: Jim Klimov <EvgenyKlimov@eaton.com>

Problem: no test for issue #11

Solution: add teststr.gsl to make check and add non-matching search_replace to test

See #11

Problem: memory leak if string.search_replace has nothing to replace

Solution: use mem_strdup instead of strdup

Fixes #11

Problem: Build can't always reasonable run binary

Solution: Build the test stage instead, since that's where
the ./gsl -v build was moved

Solution: Put the ./gsl -v  call in check: and make check: depend
on everything: to make it easy to see in Travis.

Problem: gcc is not always called gcc

Solution: Query the --version string of whatever CCNAME happens to
be. This will catch such misfits as cross compilers, and places
where gcc is invoked as plain old cc.

Problems: more improvements needed for debian packaging

Solution: list them under BSD-3-Clause

Solution: remove all mentions of pcre/*

Solution: add them

Solution: further simplify it using the .install files

Solution: run dh with --parallel

Solution: further simplify it

Problem: old and bugged PCRE version embedded

Solution: remove it. All supported builds work with a system distributed
version of PCRE, so it's not necessary anymore.
Fixes #1

Solution: use system header instead

Problem: more outdate copyrights and URLs

Solution: fix them as well

Problem: compiler warnings with GCC 7

Solution: dereference pointer
Spotted by GCC7 with -Wpointer-compare

Solution: fix -Wformat-truncation by using large enough static
buffers

Problems: no manpage, no Travis OSX job, reproducibility issue, old copyright/website

Solution: add it

Solution: set sudo to false as it's not used

Solution: nowadays the MPL-2.0 is shipped by debian in
/usr/share/common-licenses so as per guidelines only note where to
find it on the system

Solution: list bsd-3-clause just once

W: generator-scripting-language source:
   dep5-copyright-license-name-not-unique

Solution: don't depend on the exact same version, as it's not necessary

E: generator-scripting-language source:
 not-binnmuable-all-depends-any
 generator-scripting-language-examples -> generator-scripting-language

Solution: don't do it. Nowadays it's not a very useful information
anyway.

Solution: update them

Solution: add one and install it in section 1

Problem: no version for clean fork of repo to zeromq.

Problems: various packaging problems

Solution: add GSL Developers in copyright notice and as package
maintainer, and use the ZeroMQ mailing list as the contact email
address

Solution: add %undefine _debugsource_packages to the spec file as a
workaround Fedora rpmbuild changes