Introduce TEST_FPM_EXTENSION_DIR for FPM tests with shared extensions

[bukka]

More generic solution for #9643

[bukka]

@andypost Please can you test this and let me know if that works for you?

[andypost]

Thanks, will do tomorrow

[andypost]

Works for me even for php 8.0 (it has 2 arguments for method), thank you!

/mnt/testing/php8 $ TEST_FPM_EXTENSION_DIR=modules TESTS='--show-diff sapi/fpm/tests/bug77780-header-sent-error.phpt' abuild check

Build complete.
Don't forget to run 'make test'.


=====================================================================
PHP         : /mnt/testing/php8/src/php-8.0.25/sapi/cli/php 
PHP_SAPI    : cli
PHP_VERSION : 8.0.25
ZEND_VERSION: 4.0.25
PHP_OS      : Linux - Linux andy-HP 5.19.0-23-generic #24-Ubuntu SMP PREEMPT_DYNAMIC Fri Oct 14 15:39:57 UTC 2022 x86_64
INI actual  : /mnt/testing/php8/src/php-8.0.25/tmp-php.ini
More .INIs  :   
---------------------------------------------------------------------
PHP         : /mnt/testing/php8/src/php-8.0.25/sapi/phpdbg/phpdbg 
PHP_SAPI    : phpdbg
PHP_VERSION : 8.0.25
ZEND_VERSION: 4.0.25
PHP_OS      : Linux - Linux andy-HP 5.19.0-23-generic #24-Ubuntu SMP PREEMPT_DYNAMIC Fri Oct 14 15:39:57 UTC 2022 x86_64
INI actual  : /mnt/testing/php8/src/php-8.0.25/tmp-php.ini
More .INIs  : 
---------------------------------------------------------------------
CWD         : /mnt/testing/php8/src/php-8.0.25
Extra dirs  : 
VALGRIND    : Not used
=====================================================================
Running selected tests.
PASS FPM: bug77780 - Headers already sent error incorrectly emitted [sapi/fpm/tests/bug77780-header-sent-error.phpt] 
=====================================================================
Number of tests :    1                 1
Tests skipped   :    0 (  0.0%) --------
Tests warned    :    0 (  0.0%) (  0.0%)
Tests failed    :    0 (  0.0%) (  0.0%)
Tests passed    :    1 (100.0%) (100.0%)
---------------------------------------------------------------------
Time taken      :    1 seconds
=====================================================================
NOTE: We have skipped quite a lot tests, see disabled-tests.list.

[andypost]

@bukka what's left here to get it merged?

[andypost]

needs rebase

[bukka]

Sorry for the delay. Merged to PHP-8.0+ via db2d32f