Remove invalid macro starting with _ from libfdt_env.h

libfdt_env.h in the device tree compiler currently defines a _B() macro. This is in the
namespace reserved for the implementation, and Cygwin's ctype.h actually defines a macro
with this name. This renames _B to EXTRACT_BYTE.

Signed-off-by: Bert Kenward <bert.kenward@broadcom.com>

libfdt/libfdt_env.h

@@ -5,25 +5,25 @@
 #include <stdint.h>
 #include <string.h>
 
-#define _B(n)	((unsigned long long)((uint8_t *)&x)[n])
+#define EXTRACT_BYTE(n)	((unsigned long long)((uint8_t *)&x)[n])
 static inline uint16_t fdt16_to_cpu(uint16_t x)
 {
-	return (_B(0) << 8) | _B(1);
+	return (EXTRACT_BYTE(0) << 8) | EXTRACT_BYTE(1);
 }
 #define cpu_to_fdt16(x) fdt16_to_cpu(x)
 
 static inline uint32_t fdt32_to_cpu(uint32_t x)
 {
-	return (_B(0) << 24) | (_B(1) << 16) | (_B(2) << 8) | _B(3);
+	return (EXTRACT_BYTE(0) << 24) | (EXTRACT_BYTE(1) << 16) | (EXTRACT_BYTE(2) << 8) | EXTRACT_BYTE(3);
 }
 #define cpu_to_fdt32(x) fdt32_to_cpu(x)
 
 static inline uint64_t fdt64_to_cpu(uint64_t x)
 {
-	return (_B(0) << 56) | (_B(1) << 48) | (_B(2) << 40) | (_B(3) << 32)
+	return (EXTRACT_BYTE(0) << 56) | (EXTRACT_BYTE(1) << 48) | (EXTRACT_BYTE(2) << 40) | (EXTRACT_BYTE(3) << 32)
-		| (_B(4) << 24) | (_B(5) << 16) | (_B(6) << 8) | _B(7);
+		| (EXTRACT_BYTE(4) << 24) | (EXTRACT_BYTE(5) << 16) | (EXTRACT_BYTE(6) << 8) | EXTRACT_BYTE(7);
 }
 #define cpu_to_fdt64(x) fdt64_to_cpu(x)
-#undef _B
+#undef EXTRACT_BYTE
 
 #endif /* _LIBFDT_ENV_H */