When building in strict mode (e.g. -std=c11), compilation of
main/debug_gdb_scripts.c fails because asm() is not a standard top level
statement. __asm__() however can be reserved by the compiler even in strict
mode.
Partially fixes GH-21215. IR needs a similar fix (dstogov/ir#128).
Closes GH-21226.
This inlines .gdbinit and php_gdb.py in the .debug_gdb_scripts section of the PHP binary so that GDB can auto-load them regardless of the current directory or the availability of the PHP source code (albeit some functionalities of php_gdb.py currently rely on the source being available).
