Robustify toolchain string matching

cmake/common/px4_base.cmake

@@ -512,7 +512,7 @@ function(px4_add_common_flags)
 		list(APPEND warnings -Wframe-larger-than=1024)
 	endif()
 
-	if (${CMAKE_C_COMPILER_ID} STREQUAL "Clang")
+	if (${CMAKE_C_COMPILER_ID} MATCHES ".*Clang.*")
 		# QuRT 6.4.X compiler identifies as Clang but does not support this option
 		if (NOT ${OS} STREQUAL "qurt")
 			list(APPEND warnings
@@ -540,7 +540,7 @@ function(px4_add_common_flags)
 		-fdata-sections
 		)
 
-	if (NOT ${CMAKE_C_COMPILER_ID} STREQUAL "Clang")
+	if (NOT ${CMAKE_C_COMPILER_ID} MATCHES ".*Clang.*")
 		list(APPEND optimization_flags
 			-fno-strength-reduce
 			-fno-builtin-printf
@@ -554,7 +554,7 @@ function(px4_add_common_flags)
 		-Wnested-externs
 		)
 
-	if (NOT ${CMAKE_C_COMPILER_ID} STREQUAL "Clang")
+	if (NOT ${CMAKE_C_COMPILER_ID} MATCHES ".*Clang.*")
 		list(APPEND c_warnings
 			-Wold-style-declaration
 			-Wmissing-parameter-type
@@ -633,16 +633,10 @@ function(px4_add_common_flags)
 		-DCONFIG_ARCH_BOARD_${board_config}
 		)
 
-	if (NOT ${CMAKE_C_COMPILER_ID} STREQUAL "Clang")
-		set(added_exe_link_flags
-			-Wl,--warn-common
-			-Wl,--gc-sections
-			)
-	else()
+
 		set(added_exe_link_flags
 			-Wl,--warn-common
 			)
-	endif()
 
 	# output
 	foreach(var ${inout_vars})