subprojects: fix libplacebo build on freebsd

.gitignore

@@ -1,2 +1,3 @@
 /subprojects/*
-!/subprojects/libplacebo.wrap
+!/subprojects/packagefiles/
+!/subprojects/*.wrap

meson.build

@@ -2,7 +2,7 @@ project('mpv',
         'c',
         license: ['GPL2+', 'LGPL2.1+'],
         version: files('./VERSION'),
-        meson_version: '>=0.62.0',
+        meson_version: '>=0.63.0',
         default_options: [
             'buildtype=debugoptimized',
             'b_lundef=false',

subprojects/libplacebo.wrap

@@ -4,3 +4,4 @@ url = https://code.videolan.org/videolan/libplacebo.git
 revision = v6.338.0
 depth = 1
 clone-recursive = true
+diff_files = fix-freebsd.diff

subprojects/packagefiles/fix-freebsd.diff

@@ -0,0 +1,29 @@
+diff --git a/meson.build b/meson.build
+index e339cf33..bc3fe0e7 100644
+--- a/meson.build
++++ b/meson.build
+@@ -384,11 +384,12 @@ build_opts = [
+
+ link_args = []
+
++host_system = host_machine.system()
+ cc = meson.get_compiler('c')
+ cxx = meson.get_compiler('cpp')
+
+ c_opts = [
+-  '-D_ISOC99_SOURCE', '-D_ISOC11_SOURCE', '-D_GNU_SOURCE', '-D_XOPEN_SOURCE=700',
++  '-D_ISOC99_SOURCE', '-D_ISOC11_SOURCE', '-D_GNU_SOURCE',
+   '-U__STRICT_ANSI__', '-Wmissing-prototypes',
+
+   # Warnings to ignore
+@@ -399,6 +400,10 @@ c_opts = [
+   '-Werror=implicit-function-declaration',
+ ]
+
++if host_system != 'freebsd'
++  c_opts += ['-D_XOPEN_SOURCE=700']
++endif
++
+ if cc.has_argument('-Wincompatible-pointer-types')
+   c_opts += ['-Werror=incompatible-pointer-types']
+ endif