Fix setting/detecting Fortran name-mangling

- PSBLAS is setting LowerUnderscore on windows without this

CMakeLists.txt

@@ -5,7 +5,7 @@
 # Set oldest allowable CMake version
 #-----------------------------------
 cmake_minimum_required(VERSION 3.10)
-cmake_policy(VERSION 3.10.0...3.12.4)
+cmake_policy(VERSION 3.11.1...3.13.3)
 
 set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake")
 
@@ -70,8 +70,9 @@ endif()
 #------------------------------------
 # Fortran name mangling introspection
 #------------------------------------
+include("${CMAKE_CURRENT_LIST_DIR}/cmake/CapitalizeString.cmake")
 include(FortranCInterface)
-string(TOUPPER ${FortranCInterface_GLOBAL__CASE} fc_case)
+CapitalizeString(${FortranCInterface_GLOBAL__CASE} fc_case)
 message(STATUS "Name mangling capitalization: ${fc_case}")
 message(STATUS "Name mangling fortran global suffix underscore: ${FortranCInterface_GLOBAL__SUFFIX}")
 if(FortranCInterface_GLOBAL__SUFFIX STREQUAL "")

cmake/CapitalizeString.cmake

@@ -0,0 +1,7 @@
+function(CapitalizeString string output_variable)
+  string(TOUPPER "${string}" _upper_string)
+  string(TOLOWER "${string}" _lower_string)
+  string(SUBSTRING "${_upper_string}" 0 1 _start)
+  string(SUBSTRING "${_lower_string}" 1 -1 _end)
+  set(${output_variable} "${_start}${_end}" PARENT_SCOPE)
+endfunction()