Set PDB path for Visual Studio (fmtlib#3702)

Ensure the PDB files are output into the same directory and with the same name
as the static library when using Visual Studio.

Resolves fmtlib#3701.

CMakeLists.txt

@@ -312,7 +312,15 @@ set(FMT_DEBUG_POSTFIX d CACHE STRING "Debug library postfix.")
 set_target_properties(fmt PROPERTIES
   VERSION ${FMT_VERSION} SOVERSION ${CPACK_PACKAGE_VERSION_MAJOR}
   PUBLIC_HEADER "${FMT_HEADERS}"
-  DEBUG_POSTFIX "${FMT_DEBUG_POSTFIX}")
+  DEBUG_POSTFIX "${FMT_DEBUG_POSTFIX}"
+
+  # Workaround for Visual Studio 2017:
+  # Ensure the .pdb is created with the same name and in the same directory
+  # as the .lib. Newer VS versions already do this by default, but there is no
+  # harm in setting it for those too. Ignored by other generators.
+  COMPILE_PDB_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}"
+  COMPILE_PDB_NAME "fmt"
+  COMPILE_PDB_NAME_DEBUG "fmt${FMT_DEBUG_POSTFIX}")
 
 # Set FMT_LIB_NAME for pkg-config fmt.pc. We cannot use the OUTPUT_NAME target
 # property because it's not set by default.