doxygen: Generate Doxygen for NIR

Now, one can do the following to generate and read the nir Doxygen:
cd $MESA_TOP/doxygen
make
firefox nir/index.html

Update v2:
Correct TAGFILES in nir.doxy

Signed-off-by: Elie TOURNIER <tournier.elie@gmail.com>
Reviewed-by: Rhys Kidd <rhyskidd@gmail.com>

[Emil Velikov] v3: Rebase.
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/doxygen/nir.doxy b/doxygen/nir.doxy
new file mode 100644
index 0000000..cad7380
--- /dev/null
+++ b/doxygen/nir.doxy
@@ -0,0 +1,50 @@
+# Doxyfile 0.1
+
+@INCLUDE               = common.doxy
+
+#---------------------------------------------------------------------------
+# General configuration options
+#---------------------------------------------------------------------------
+PROJECT_NAME           = "Mesa NIR module"
+#---------------------------------------------------------------------------
+# Configuration options related to the input files
+#---------------------------------------------------------------------------
+INPUT                  = ../src/compiler/nir
+FILE_PATTERNS          = *.c *.cpp *.h
+RECURSIVE              = NO
+EXCLUDE                =
+EXCLUDE_PATTERNS       =
+EXAMPLE_PATH           =
+EXAMPLE_PATTERNS       =
+EXAMPLE_RECURSIVE      = NO
+IMAGE_PATH             =
+INPUT_FILTER           =
+FILTER_SOURCE_FILES    = NO
+#---------------------------------------------------------------------------
+# Configuration options related to the HTML output
+#---------------------------------------------------------------------------
+HTML_OUTPUT            = nir
+#---------------------------------------------------------------------------
+# Configuration options related to the preprocessor
+#---------------------------------------------------------------------------
+ENABLE_PREPROCESSING   = YES
+MACRO_EXPANSION        = NO
+EXPAND_ONLY_PREDEF     = NO
+SEARCH_INCLUDES        = YES
+INCLUDE_PATH           = ../include/
+INCLUDE_FILE_PATTERNS  =
+PREDEFINED             =
+EXPAND_AS_DEFINED      =
+SKIP_FUNCTION_MACROS   = YES
+#---------------------------------------------------------------------------
+# Configuration::additions related to external references
+#---------------------------------------------------------------------------
+TAGFILES               = glsl.tag=../glsl \
+                         main.tag=../main \
+                         math.tag=../math \
+                         swrast.tag=../swrast \
+                         swrast_setup.tag=../swrast_setup \
+                         tnl.tag=../tnl \
+                         tnl_dd.tag=../tnl_dd \
+                         vbo.tag=../vbo
+GENERATE_TAGFILE       = nir.tag