[gtk/docs-gtk-org] glib: Add section on cross-compiling GLib

[Emmanuele Bassi <ebassi src gnome org>]

commit e5adad0e5877ac0a6c7e4cc321d5209ad946c6ed
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Aug 18 18:25:02 2021 +0100

    glib: Add section on cross-compiling GLib

 glib/glib/cross-compiling.md | 88 ++++++++++++++++++++++++++++++++++++++++++++
 glib/glib/glib.toml.in       |  1 +
 glib/glib/meson.build        |  1 +
 3 files changed, 90 insertions(+)
---
diff --git a/glib/glib/cross-compiling.md b/glib/glib/cross-compiling.md
new file mode 100644
index 0000000000..90e7f41ff4
--- /dev/null
+++ b/glib/glib/cross-compiling.md
@@ -0,0 +1,88 @@
+Title: Cross-compiling the GLib package
+
+# Cross-compiling the GLib Package
+       
+## Building the Library for a different architecture
+
+Cross-compilation is the process of compiling a program or library on a
+different architecture or operating system then it will be run upon. GLib is
+slightly more difficult to cross-compile than many packages because much of
+GLib is about hiding differences between different systems.
+
+These notes cover things specific to cross-compiling GLib; for general
+information about cross-compilation, see the [Meson
+documentation](http://mesonbuild.com/Cross-compilation.html).
+
+GLib tries to detect as much information as possible about the target system
+by compiling and linking programs without actually running anything;
+however, some information GLib needs is not available this way. This
+information needs to be provided to meson via a ‘cross file’.
+
+As an example of using a cross file, to cross compile for the ‘MingW32’
+Win64 runtime environment on a Linux system, create a file `cross_file.txt`
+with the following contents:
+
+```
+[host_machine]
+system = 'windows'
+cpu_family = 'x86_64'
+cpu = 'x86_64'
+endian = 'little'
+
+[properties]
+c_args = []
+c_link_args = []
+
+[binaries]
+c = 'x86_64-w64-mingw32-gcc'
+cpp = 'x86_64-w64-mingw32-g++'
+ar = 'x86_64-w64-mingw32-ar'
+ld = 'x86_64-w64-mingw32-ld'
+objcopy = 'x86_64-w64-mingw32-objcopy'
+strip = 'x86_64-w64-mingw32-strip'
+pkgconfig = 'x86_64-w64-mingw32-pkg-config'
+windres = 'x86_64-w64-mingw32-windres'
+```   
+
+Then execute the following commands:
+
+    meson setup --cross-file cross_file.txt builddir
+
+The complete list of cross properties follows. Most of these won't need to
+be set in most cases.
+
+## Cross properties
+
+`have_[function]`
+: When meson checks if a function is supported, the test can be overridden by
+  setting the `have_function` property to `true` or `false`. For example:
+
+    Checking for function "fsync" : YES
+
+  can be overridden by setting
+
+    have_fsync = false
+
+`growing_stack=[true/false]`
+: Whether the stack grows up or down. Most places will want `false`. A few
+  architectures, such as PA-RISC need `true`.
+
+`have_strlcpy=[true/false]`
+: Whether you have `strlcpy()` that matches OpenBSD. Defaults to `false`,
+  which is safe, since GLib uses a built-in version in that case.
+
+`va_val_copy=[true/false]`
+: Whether `va_list` can be copied as a pointer. If set to `false`, then
+  `memcopy()` will be used. Only matters if you don't have `va_copy()` or
+  `__va_copy()`. (So, doesn't matter for GCC.) Defaults to `true` which is
+  slightly more common than `false`.
+
+`have_c99_vsnprintf=[true/false]`
+: Whether you have a `vsnprintf()` with C99 semantics. (C99 semantics means
+  returning the number of bytes that would have been written had the output
+  buffer had enough space.) Defaults to `false`.
+
+`have_c99_snprintf=[true/false]`
+: Whether you have a `snprintf()` with C99 semantics. (C99 semantics means
+  returning the number of bytes that would have been written had the output
+  buffer had enough space.) Defaults to `false`.
diff --git a/glib/glib/glib.toml.in b/glib/glib/glib.toml.in
index 2a52846d50..742a755721 100644
--- a/glib/glib/glib.toml.in
+++ b/glib/glib/glib.toml.in
@@ -35,6 +35,7 @@ urlmap_file = "urlmap.js"
 content_files = [
   "building.md",
   "compiling.md",
+  "cross-compiling.md",
   "error-reporting.md",
   "gvariant-format-strings.md",
   "gvariant-text.md",
diff --git a/glib/glib/meson.build b/glib/glib/meson.build
index b600d62219..ffb3710499 100644
--- a/glib/glib/meson.build
+++ b/glib/glib/meson.build
@@ -1,6 +1,7 @@
 expand_content_files = [
   'building.md',
   'compiling.md',
+  'cross-compiling.md',
   'error-reporting.md',
   'gvariant-format-strings.md',
   'gvariant-text.md',