Remove Findfmt.cmake

fmt provides a cmake config files since at least version 7.0.0,
which is the minimum version supported.
Fixed some variable names, so the provided config can be used.

src/cmake/externalpackages.cmake

@@ -332,7 +332,7 @@ macro (find_or_download_fmt)
     # If an external copy wasn't found and we requested that missing
     # packages be built, or we we are forcing a local copy to be built, then
     # download and build it.
-    if ((BUILD_MISSING_FMT AND NOT FMT_FOUND) OR BUILD_FMT_FORCE)
+    if ((BUILD_MISSING_FMT AND NOT fmt_FOUND) OR BUILD_FMT_FORCE)
         message (STATUS "Downloading local fmtlib/fmt")
         set (FMT_INSTALL_DIR "${PROJECT_SOURCE_DIR}/ext/fmt")
         set (FMT_GIT_REPOSITORY "https://github.com/fmtlib/fmt")
@@ -350,16 +350,18 @@ macro (find_or_download_fmt)
         endif ()
         set (FMT_INCLUDE_DIR "${FMT_INSTALL_DIR}/include")
         set (OIIO_USING_FMT_LOCAL TRUE)
+        set (fmt_VERSION ${BUILD_FMT_VERSION})
     else ()
+        get_target_property(FMT_INCLUDE_DIR fmt::fmt INTERFACE_INCLUDE_DIRECTORIES)
         set (OIIO_USING_FMT_LOCAL FALSE)
+        checked_find_package (fmt REQUIRED
+                              VERSION_MIN 7.0)
     endif ()
-    checked_find_package (fmt REQUIRED
-                          VERSION_MIN 7.0)
 endmacro()
 
 find_or_download_fmt()
 
-if (FMT_VERSION VERSION_EQUAL 90100
+if (fmt_VERSION VERSION_EQUAL 9.1.0
         AND GCC_VERSION VERSION_GREATER 0.0 AND NOT GCC_VERSION VERSION_GREATER 7.2)
     message (WARNING "${ColorRed}fmt 9.1 is known to not work with gcc <= 7.2${ColorReset}")
 endif ()

src/include/CMakeLists.txt

@@ -66,13 +66,13 @@ install (FILES ${detail_headers}
 
 if (INTERNALIZE_FMT OR OIIO_USING_FMT_LOCAL)
     set (fmt_headers
-         ${FMT_INCLUDES}/fmt/core.h
-         ${FMT_INCLUDES}/fmt/format-inl.h
-         ${FMT_INCLUDES}/fmt/format.h
-         ${FMT_INCLUDES}/fmt/ostream.h
-         ${FMT_INCLUDES}/fmt/printf.h )
-    if (fmt_VERSION VERSION_GREATER_EQUAL 90000)
-        list (APPEND fmt_headers ${FMT_INCLUDES}/fmt/std.h)
+         ${FMT_INCLUDE_DIR}/fmt/core.h
+         ${FMT_INCLUDE_DIR}/fmt/format-inl.h
+         ${FMT_INCLUDE_DIR}/fmt/format.h
+         ${FMT_INCLUDE_DIR}/fmt/ostream.h
+         ${FMT_INCLUDE_DIR}/fmt/printf.h )
+    if (fmt_VERSION VERSION_GREATER_EQUAL 9)
+        list (APPEND fmt_headers ${FMT_INCLUDE_DIR}/fmt/std.h)
     endif ()
     file (COPY ${fmt_headers}
           DESTINATION ${CMAKE_BINARY_DIR}/include/OpenImageIO/detail/fmt)
@@ -85,7 +85,7 @@ else ()
         file (WRITE "${CMAKE_BINARY_DIR}/include/OpenImageIO/detail/fmt/${f}"
                     "#include <fmt/${f}>")
     endforeach ()
-    if (fmt_VERSION VERSION_GREATER_EQUAL 90000)
+    if (fmt_VERSION VERSION_GREATER_EQUAL 9)
         list (APPEND fmt_headers ${CMAKE_BINARY_DIR}/include/OpenImageIO/detail/fmt/std.h)
         file (WRITE "${CMAKE_BINARY_DIR}/include/OpenImageIO/detail/fmt/std.h"
                     "#include <fmt/std.h>")