Fix build with GCC 14 and binutils >= 2.40 on Linux

[blshkv]

Problem

Building AMX Mod X on modern Linux toolchains (GCC 14 + binutils 2.40+) fails with five distinct errors. GCC 14 tightened several diagnostics to hard errors, and binutils 2.40 made --error-rwx-segments the default, turning text relocations in shared libraries into linker errors (the same issue macOS already handles via -Wl,-read_only_relocs,suppress).

Fixes

• compiler/libpc300/prefix.c — declare end as const char * in br_extract_dir() and br_extract_prefix(). strrchr() returns const char * when its input is const char *; GCC 14 promotes -Wdiscarded-qualifiers to an error.

• compiler/libpc300/AMBuilder — add -Wl,-z,notext on Linux. The i386 sources are compiled without -fPIC; binutils ≥ 2.40 made --error-rwx-segments the default, causing the link to fail with text relocation errors.

• amxmodx/AMBuilder — add an elif builder.target_platform == 'linux' block with -Wl,-z,notext. The macOS branch already uses -Wl,-read_only_relocs,suppress for the same reason; Linux now needs the equivalent.

• modules/regex/AMBuilder — add -Wl,-z,notext on Linux when linking the pre-built lib_linux/libpcre.a, which was built without -fPIC and therefore contains text relocations that binutils ≥ 2.40 rejects.

• modules/sqlite/AMBuilder — add -Wl,-z,notext on Linux and suppress -Wno-misleading-indentation -Wno-return-local-addr in binary.compiler.cflags. These are false-positive warnings triggered by the vendored SQLite amalgamation (third_party/sqlite/sqlite3.c) under GCC 14.

Tested on

Gentoo Linux, GCC 14, binutils 2.46, targeting i386.