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

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

commit ea0c4040324c62a514cc1da548a17ac4165d40bf
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.

 win32/introspection-msvc.mak | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/win32/introspection-msvc.mak b/win32/introspection-msvc.mak
index e395a2de3..ad276d980 100644
--- a/win32/introspection-msvc.mak
+++ b/win32/introspection-msvc.mak
@@ -42,10 +42,19 @@ 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
 
 VALID_PKG_CONFIG_PATH = FALSE