[gtkmm/gtkmm-3-24] NMake Makefiles: Update build info

[Chun-wei Fan <fanchunwei src gnome org>]

commit f390f7ff995b6ce000e8a6c9238351f38bda7365
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed Apr 8 19:13:28 2020 +0800

    NMake Makefiles: Update build info
    
    Tell people about the build options USE_MESON_LIBS and
    GMMPROC[_PANGO|_ATK]_DIR.

 MSVC_NMake/info-msvc.mak | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
---
diff --git a/MSVC_NMake/info-msvc.mak b/MSVC_NMake/info-msvc.mak
index 3e7b7813..50ef9119 100644
--- a/MSVC_NMake/info-msvc.mak
+++ b/MSVC_NMake/info-msvc.mak
@@ -26,6 +26,22 @@ help:
        @echo and so on; and ^$(platform) is Win32 for 32-bit builds and x64 for
        @echo x64 builds.
        @echo.
+       @echo USE_MESON_LIBS: Use this if linking to Meson-built
+       @echo variants of glibmm, pangomm and libsigc++ is desired.
+       @echo By using this option, pangomm, atkmm and cairomm
+       @echo should be linked to the Meson-built variants of
+       @echo glibmm and libsigc++ as well.
+       @echo.
+       @echo GMMPROC_DIR, GMMPROC_PANGO_DIR, GMMPROC_ATK_DIR:
+       @echo Required if building directly from a GIT checkout,
+       @echo or re-generating the source files from the .hg/.ccg
+       @echo files.  GMMPROC_PANGO_DIR and GMMPROC_ATK_DIR are by
+       @echo default in 
^$(GMMPROC_DIR)/../../pangomm-$(PANGOMM_MAJOR_VERSION).$(PANGOMM_MINOR_VERSION)/proc/m4
+       @echo and ^$(GMMPROC_DIR)/../../atkmm-$(ATKMM_MAJOR_VERSION).$(ATKMM_MINOR_VERSION)/proc/m4 
respectively.
+       @echo PERL with XML::Parser and some common *nix  commands
+       @echo are required, as well as the .m4 and PERL files from
+       @echo glibmm, atkmm and pangomm, which will be used by
+       @echo gmmproc.
        @echo ------
        @echo Possible options include the following:
        @echo.