cannot build against gimp 3 with makefile

[classabbyamp]

HOST=gimp is hardcoded in several places, patching those to gimp3 allows it to work with gimp 2.99/3.0

--- a/src/Makefile
+++ b/src/Makefile
@@ -577,11 +577,11 @@
 # G'MIC-Qt.
 #----------
 gimp: gmic_qt_files CImg.h gmic_stdlib_community.h
-	cd ../gmic-qt && $(QMAKE) CONFIG+=release GMIC_PATH=$(SRC_PATH) PRERELEASE=$(PRERELEASE) GMIC_DYNAMIC_LINKING=off HOST=gimp gmic_qt.pro && $(MAKE)
+	cd ../gmic-qt && $(QMAKE) CONFIG+=release GMIC_PATH=$(SRC_PATH) PRERELEASE=$(PRERELEASE) GMIC_DYNAMIC_LINKING=off HOST=gimp3 gmic_qt.pro && $(MAKE)
 	@echo "Executable 'gmic_gimp_qt' has been successfully compiled in '../gmic-qt/'."
 
 gimp_debug :  gmic_qt_files CImg.h gmic_stdlib_community.h
-	cd ../gmic-qt && $(QMAKE) CONFIG+=debug GMIC_PATH=$(SRC_PATH) ASAN=on PRERELEASE=$(PRERELEASE) GMIC_DYNAMIC_LINKING=off HOST=gimp gmic_qt.pro && $(MAKE)
+	cd ../gmic-qt && $(QMAKE) CONFIG+=debug GMIC_PATH=$(SRC_PATH) ASAN=on PRERELEASE=$(PRERELEASE) GMIC_DYNAMIC_LINKING=off HOST=gimp3 gmic_qt.pro && $(MAKE)
 	@echo "Executable 'gmic_gimp_qt' has been successfully compiled in '../gmic-qt/'."
 
 gmic_qt: gmic_qt_files CImg.h gmic_stdlib_community.h
@@ -619,7 +619,7 @@
 # G'MIC-Qt (shared).
 #-------------------
 gimp_shared: gmic_qt_files CImg.h gmic_stdlib_community.h
-	cd ../gmic-qt && $(QMAKE) CONFIG+=release GMIC_PATH=$(SRC_PATH) PRERELEASE=$(PRERELEASE) GMIC_DYNAMIC_LINKING=on HOST=gimp gmic_qt.pro && $(MAKE)
+	cd ../gmic-qt && $(QMAKE) CONFIG+=release GMIC_PATH=$(SRC_PATH) PRERELEASE=$(PRERELEASE) GMIC_DYNAMIC_LINKING=on HOST=gimp3 gmic_qt.pro && $(MAKE)
 	@echo "Executable 'gmic_gimp_qt' has been successfully compiled in '../gmic-qt/'."
 
 gmic_qt_shared: gmic_qt_files CImg.h gmic_stdlib_community.h