Check if -mfpu=neon is available for compiling the NEON mixer

CMakeLists.txt

@@ -364,6 +364,7 @@ SET(SSE_SWITCH "")
 SET(SSE2_SWITCH "")
 SET(SSE3_SWITCH "")
 SET(SSE4_1_SWITCH "")
+SET(FPU_NEON_SWITCH "")
 IF(NOT MSVC)
     CHECK_C_COMPILER_FLAG(-msse HAVE_MSSE_SWITCH)
     IF(HAVE_MSSE_SWITCH)
@@ -381,6 +382,10 @@ IF(NOT MSVC)
     IF(HAVE_MSSE4_1_SWITCH)
         SET(SSE4_1_SWITCH "-msse4.1")
     ENDIF()
+    CHECK_C_COMPILER_FLAG(-mfpu=neon HAVE_MFPU_NEON_SWITCH)
+    IF(HAVE_MFPU_NEON_SWITCH)
+        SET(FPU_NEON_SWITCH "-mfpu=neon")
+    ENDIF()
 ENDIF()
 
 CHECK_C_SOURCE_COMPILES("int foo(const char *str, ...) __attribute__((format(printf, 1, 2)));
@@ -766,8 +771,11 @@ IF(HAVE_ARM_NEON_H)
     IF(ALSOFT_CPUEXT_NEON)
         SET(HAVE_NEON 1)
         SET(ALC_OBJS  ${ALC_OBJS} Alc/mixer_neon.c)
+        IF(FPU_NEON_SWITCH)
+            SET_SOURCE_FILES_PROPERTIES(Alc/mixer_neon.c PROPERTIES
+                                        COMPILE_FLAGS "${FPU_NEON_SWITCH}")
+        ENDIF()
         SET(CPU_EXTS "${CPU_EXTS}, Neon")
-        SET_SOURCE_FILES_PROPERTIES(Alc/mixer_neon.c PROPERTIES COMPILE_FLAGS -mfpu=neon)
     ENDIF()
 ENDIF()
 IF(ALSOFT_REQUIRE_NEON AND NOT HAVE_NEON)