Avoid static linking conflicts with libblkid

When static linking, it's not possible to have two functions with the
same name in different libraries:

	= note: /nix/store/s2cjhni3s6shh0n35ay1hpj8d85k44qk-x86_64-unknown-linux-musl-binutils-2.43.1/bin/x86_64-unknown-linux-musl-ld: /nix/store/zwid05lzfy46k32xljb2alh0gq7ys58a-util-linux-minimal-static-x86_64-unknown-linux-musl-2.39.4-lib/lib/libblkid.a(libcommon_la-crc32c.o): in function `crc32c':
	        (.text+0x0): multiple definition of `crc32c'; ./libbcachefs.a(tools-util.o):/build/source/c_src/tools-util.c:484: first defined here
	        collect2: error: ld returned 1 exit status

Work around this by avoiding a known name collision with a function in
libblkid.

Closes: #311
Signed-off-by: Alyssa Ross <[email protected]>
Signed-off-by: Kent Overstreet <[email protected]>

c_src/tools-util.h

@@ -174,6 +174,8 @@ struct fiemap_extent fiemap_iter_next(struct fiemap_iter *);
 
 char *strcmp_prefix(char *, const char *);
 
+/* Avoid conflicts with libblkid's crc32 function in static builds */
+#define crc32c bch_crc32c
 u32 crc32c(u32, const void *, size_t);
 
 char *dev_to_name(dev_t);