meson: Add support for read-only text segment on x86

Port of 6dfc5e28f7 (configure.ac: Add support to enable read-only text
segment on x86.) to Meson.

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>

meson.build

@@ -50,6 +50,7 @@ with_tests = get_option('build-tests')
 with_valgrind = get_option('valgrind')
 with_libunwind = get_option('libunwind')
 with_asm = get_option('asm')
+with_glx_read_only_text = get_option('glx-read-only-text')
 with_osmesa = get_option('osmesa')
 with_swr_arches = get_option('swr-arches')
 with_tools = get_option('tools')
@@ -874,6 +875,10 @@ if with_asm
       with_asm_arch = 'x86'
       pre_args += ['-DUSE_X86_ASM', '-DUSE_MMX_ASM', '-DUSE_3DNOW_ASM',
                    '-DUSE_SSE_ASM']
+
+      if with_glx_read_only_text
+         pre_args += ['-DGLX_X86_READONLY_TEXT']
+      endif
     endif
   elif host_machine.cpu_family() == 'x86_64'
     if system_has_kms_drm

meson_options.txt

@@ -224,6 +224,12 @@ option(
   value : true,
   description : 'Build assembly code if possible'
 )
+option(
+   'glx-read-only-text',
+   type : 'boolean',
+   value : false,
+   description : 'Disable writable .text section on x86 (decreases performance)'
+)
 option(
   'llvm',
   type : 'combo',