build: add GCC 10 version detection

Lets add GCC 10 detection to the build system as distributions like Fedora 32 have started shipping with it.
Some tools like mtd-utils need work to compile under GCC10, but that will be next step.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
(cherry picked from commit 835d1c6)

include/prereq-build.mk

@@ -28,15 +28,16 @@ $(eval $(call TestHostCommand,proper-umask, \
 
 $(eval $(call SetupHostCommand,gcc, \
 	Please install the GNU C Compiler (gcc) 4.8 or later, \
-	$(CC) -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?)', \
-	gcc -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?)', \
+	$(CC) -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?|10\.?)', \
+	gcc -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?|10\.?)', \
 	gcc48 --version | grep gcc, \
 	gcc49 --version | grep gcc, \
 	gcc5 --version | grep gcc, \
 	gcc6 --version | grep gcc, \
 	gcc7 --version | grep gcc, \
 	gcc8 --version | grep gcc, \
 	gcc9 --version | grep gcc, \
+	gcc10 --version | grep gcc, \
 	gcc --version | grep -E 'Apple.(LLVM|clang)' ))
 
 $(eval $(call TestHostCommand,working-gcc, \
@@ -47,15 +48,16 @@ $(eval $(call TestHostCommand,working-gcc, \
 
 $(eval $(call SetupHostCommand,g++, \
 	Please install the GNU C++ Compiler (g++) 4.8 or later, \
-	$(CXX) -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?)', \
-	g++ -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?)', \
+	$(CXX) -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?|10\.?)', \
+	g++ -dumpversion | grep -E '^(4\.[8-9]|[5-9]\.?|10\.?)', \
 	g++48 --version | grep g++, \
 	g++49 --version | grep g++, \
 	g++5 --version | grep g++, \
 	g++6 --version | grep g++, \
 	g++7 --version | grep g++, \
 	g++8 --version | grep g++, \
 	g++9 --version | grep g++, \
+	g++10 --version | grep g++, \
 	g++ --version | grep -E 'Apple.(LLVM|clang)' ))
 
 $(eval $(call TestHostCommand,working-g++, \