MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

R_MIPS_PC32 is a GNU extension, its definition is available in glibc
only since 2.39 (released in 2024), and not available in musl libc yet.
Provide our own definition for R_MIPS_PC32 and use it if necessary to
fix relocs tool building on musl and older glibc systems.

Fixes: ff79d31 ("mips: Add support for PC32 relocations in vmlinux")
Signed-off-by: Yao Zi <me@ziyao.cc>
Link: https://patch.msgid.link/20260202041610.61389-1-me@ziyao.cc
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Author: ziyao233

arch/mips/boot/tools/relocs.h

@@ -29,6 +29,13 @@ void die(char *fmt, ...);
 #define R_MIPS_PC26_S2		61
 #endif
 
+/*
+ * GNU extension that available in glibc only since 2023, not available on musl.
+ */
+#ifndef R_MIPS_PC32
+#define R_MIPS_PC32		248
+#endif
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 enum symtype {