Update adding Linux build for Airmap

QGCExternalLibs.pri

@@ -161,6 +161,12 @@ contains (DEFINES, DISABLE_AIRMAP) {
                 LIBS += -L$${AIRMAPD_PATH}/macOS/Qt.5.9 -lairmap-qt
                 DEFINES += QGC_AIRMAP_ENABLED
             }
+        } else:LinuxBuild {
+            exists($${AIRMAPD_PATH}/linux/Qt.5.9) {
+                message("Including support for AirMap for Linux")
+                LIBS += -L$${AIRMAPD_PATH}/linux/Qt.5.9 -lairmap-qt
+                DEFINES += QGC_AIRMAP_ENABLED
+            }
         } else {
             message("Skipping support for Airmap (unsupported platform)")
         }

v2.0 @ 1b0dc473

-Subproject commit f36b9c4c5c0c9b6d33621779469de0c1e7eea457
+Subproject commit 1b0dc4732864efadd72f9bfc89762bdb956c8638

src/Airmap/AirMapFlightPlanManager.cc

@@ -435,7 +435,7 @@ AirMapFlightPlanManager::_updateRulesAndFeatures(std::vector<RuleSet::Id>& rules
                                     break;
                                 case AirspaceRuleFeature::Float:
                                     //-- Sanity check for floats
-                                    if(isfinite(feature->value().toFloat())) {
+                                    if(std::isfinite(feature->value().toFloat())) {
                                         features[feature->name().toStdString()] = RuleSet::Feature::Value(feature->value().toFloat());
                                     }
                                     break;