[librsvg/msvc-introspection-config] NMake Makefiles: Allow one to pass in introspection paths

[Marge Bot <marge-bot src gnome org>]

commit 07e299317db70941f15b0cfc3b81173ecae90de8
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Thu Apr 28 10:46:13 2022 +0800

    NMake Makefiles: Allow one to pass in introspection paths
    
    Improve flexibility for the builds so that one can specify paths for
    g-ir-scanner and g-ir-compiler (via G_IR_[SCANNER|COMPILER].  Also allow one
    to specify paths to find dependent .gir and .typelib files via G_IR_INCLUDEDIR
    and G_IR_TYPELIBDIR respectively.
    
    The current way of specifying PREFIX and/or BINDIR without specifying any of
    the above will continue to work as they did previously.
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/693>

 win32/introspection-msvc.mak | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/win32/introspection-msvc.mak b/win32/introspection-msvc.mak
index 2e7b775af..559d1459c 100644
--- a/win32/introspection-msvc.mak
+++ b/win32/introspection-msvc.mak
@@ -43,10 +43,18 @@ PKG_CONFIG=pkg-config
 GIR_SUBDIR = share\gir-1.0
 GIR_TYPELIBDIR = lib\girepository-1.0
 
+!ifndef G_IR_SCANNER
 G_IR_SCANNER = $(BINDIR)\g-ir-scanner
+!endif
+!ifndef G_IR_COMPILER
 G_IR_COMPILER = $(BINDIR)\g-ir-compiler.exe
+!endif
+!ifndef G_IR_INCLUDEDIR
 G_IR_INCLUDEDIR = $(BINDIR)\..\$(GIR_SUBDIR)
+!endif
+!ifndef G_IR_TYPELIBDIR
 G_IR_TYPELIBDIR = $(BINDIR)\..\$(GIR_TYPELIBDIR)
+!endif
 
 # Used for generating the documentation using gi-docgen
 !ifndef GI_DOCGEN