[Documentation] Always use SVG for dot-generated doxygen images. (#136843)

Despite our attempt (build-docs.sh)
to build the documentation with SVG,
it still uses PNG https://llvm.org/doxygen/classllvm_1_1StringRef.html,

and that renders terribly on any high dpi display.

SVG leads to smasller installation and works fine
on all browser (that has been true for _a while_
https://caniuse.com/svg), so this patch just unconditionally build all
dot graphs as SVG in all subprojects and remove the option.

GitOrigin-RevId: 320ec7fa7f2ca9385e355d3e031e601a9e331e3e
diff --git a/docs/CMakeLists.txt b/docs/CMakeLists.txt
index 4cb9fb4..2e60d54 100644
--- a/docs/CMakeLists.txt
+++ b/docs/CMakeLists.txt
@@ -47,14 +47,6 @@
     set(openmp_doxygen_qhp_cust_filter_attrs "")
   endif()
 
-  option(LLVM_DOXYGEN_SVG
-    "Use svg instead of png files for doxygen graphs." OFF)
-  if (LLVM_DOXYGEN_SVG)
-    set(DOT_IMAGE_FORMAT "svg")
-  else()
-    set(DOT_IMAGE_FORMAT "png")
-  endif()
-
   configure_file(${CMAKE_CURRENT_SOURCE_DIR}/doxygen.cfg.in
     ${CMAKE_CURRENT_BINARY_DIR}/doxygen.cfg @ONLY)
 
@@ -72,7 +64,6 @@
   set(openmp_doxygen_qhelpgenerator_path)
   set(openmp_doxygen_qhp_cust_filter_name)
   set(openmp_doxygen_qhp_cust_filter_attrs)
-  set(DOT_IMAGE_FORMAT)
 
   add_custom_target(doxygen-openmp
     COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/doxygen.cfg
diff --git a/docs/doxygen.cfg.in b/docs/doxygen.cfg.in
index 6292a45..07964e9 100644
--- a/docs/doxygen.cfg.in
+++ b/docs/doxygen.cfg.in
@@ -2194,7 +2194,7 @@
 # The default value is: png.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_IMAGE_FORMAT       = @DOT_IMAGE_FORMAT@
+DOT_IMAGE_FORMAT       = svg
 
 # If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to
 # enable generation of interactive SVG images that allow zooming and panning.
diff --git a/runtime/doc/doxygen/config b/runtime/doc/doxygen/config
index 04c9667..0d8a3ec 100644
--- a/runtime/doc/doxygen/config
+++ b/runtime/doc/doxygen/config
@@ -1746,7 +1746,7 @@
 # HTML_FILE_EXTENSION to xhtml in order to make the SVG files

 # visible in IE 9+ (other browsers do not have this requirement).

 

-DOT_IMAGE_FORMAT       = png

+DOT_IMAGE_FORMAT       = svg

 

 # If DOT_IMAGE_FORMAT is set to svg, then this option can be set to YES to

 # enable generation of interactive SVG images that allow zooming and panning.