Merge pull request #3013 from blattms/backport-of-pr-3012

[backport] Make not finding Quadmath non-fatal (e.g. not available on arm64)

cmake/Modules/FindQuadmath.cmake

@@ -43,7 +43,7 @@ int main(void){
 endif()
 
 if (USE_QUADMATH AND NOT QUADMATH_FOUND)
-  message(FATAL_ERROR "Quadruple precision math support was explicitly requested but is unavailable!")
+  message(STATUS "Quadruple precision math support is unavailable! Skipping it.")
 endif()
 
 include(FindPackageHandleStandardArgs)

cmake/Modules/OpmInit.cmake

@@ -144,7 +144,7 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 
 # quadmath must be explicitly enabled
 # This needs to be in OpmInit as prereqs is called before OpmLibMain is included.
-option (USE_QUADMATH "Use high precision floating point library (slow)" ON)
+option (USE_QUADMATH "Search for high precision floating point library (normally not used)" ON)
 if (NOT USE_QUADMATH)
   set (CMAKE_DISABLE_FIND_PACKAGE_QuadMath TRUE)
 endif ()