[gdk-pixbuf] build: Improve Meson's jpeg dependency discovery on MSVC

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

commit 10883beb022ea275de5bac642b135b9f1ef534c2
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed Aug 23 12:33:27 2017 +0800

    build: Improve Meson's jpeg dependency discovery on MSVC
    
    We may be using either libjpeg-turbo or the IJG JPEG library for our
    (non-GDI+) jpeg support, so we need to also look for libjpeg.lib (the
    .lib that the IJG JPEG library produces in its MSVC build system) as
    well when we could not find jpeg.lib (the .lib that libjpeg-turbo
    produces in its CMake build system).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=785767

 meson.build |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/meson.build b/meson.build
index edd1ab9..dd42b76 100644
--- a/meson.build
+++ b/meson.build
@@ -238,6 +238,11 @@ endif
 if get_option('enable_jpeg')
   if cc.has_header('jpeglib.h')
     jpeg_dep = cc.find_library('jpeg', required: false)
+    if cc.get_id() == 'msvc' and not jpeg_dep.found()
+      # The IJG JPEG library builds the .lib file as libjpeg.lib in its MSVC build system,
+      # so look for it as well when jpeg.lib cannot be found
+      jpeg_dep = cc.find_library('libjpeg', required: false)
+    endif
     if jpeg_dep.found() and cc.has_function('jpeg_destroy_decompress', dependencies: jpeg_dep)
       enabled_loaders += 'jpeg'
       loaders_deps += jpeg_dep