Build multiple php versions

[ebikt]

There can be multiple PHP versions installed at once on Debian Linux distributions. PHP maintainer for debian has repositories for this hosted on deb.sury.org. User needs to copy PHP-CPP source to be able to build phpcpp for multiple
php versions at once. Moreover they need patch soname of output .so, so that multiple versions can be used simultaneously.

This merge requests aims to fix that, by introducing Makefile variables:

• LIBRARY_NAME (default libphpcpp
• BUILD_DIR (default build)
• LDCONFIG (default $(shell which ldconfig 2>/dev/null))

This change is backward compatible, i.e., behaviour of Makefile does not change when user user uses default values, with one exception: resulting .so and .a are now stored in root of $(BUILD_DIR) instead of root of project, so that multiple versions can be built at once, even if user wants them to have same name.

Excerpt from my makefile, that wraps PHP-CPP makefile for building for multiple PHP versions,
main line is the MAKEPHPCPP variable which expects PHP version in $* and expands to
call to PHP-CPP Makefile with properly set build variables.

all: $(addprefix do-all-, $(PHP_VERSIONS))
install: $(addprefix install-all-,$(PHP_VERSIONS))

PHP_CONFIG=php-config$*
DEBDEV=debian/phpcpp-php$*-dev
DEBLIB=debian/libphpcpp-php$*
#Relative to DEBDEV
DEBLIB_REL=../../$(DEBLIB)

MAKEPHPCPP=$(MAKE) -C PHP-CPP BUILD_DIR=build-$* PHP_CONFIG='$(PHP_CONFIG)' LIBRARY_NAME='libphpcpp$*'

call-all-%:
        $(MAKEPHPCPP)

do-all-%: call-all-%
        true

call-install-%:
        $(MAKEPHPCPP) install \
                LDCONFIG="" \
                INSTALL_LIB="../$(DEBDEV)/usr/lib/$(DEB_HOST_GNU_TYPE)/" \
                INSTALL_HEADERS="../$(DEBDEV)/`$(PHP_CONFIG) --include-dir`" \
                CP="cp -af"

do-install-%: call-install-%
        mkdir -p '$(DEBLIB)/usr/lib/$(DEB_HOST_GNU_TYPE)'
        set -e; cd '$(DEBDEV)'; \
        for F in 'usr/lib/$(DEB_HOST_GNU_TYPE)/libphpcpp$*.so.'*; do mv "$$F" '$(DEBLIB_REL)/'"$$F"; done
        mkdir -p '$(DEBDEV)/usr/share/pkgconfig/'
        sh phpcpp.pc.in $* > '$(DEBDEV)/usr/share/pkgconfig/phpcpp-php$*.pc'