tree-wide: include asm/sgidefs.h to make _MIPS_SIM_ABI32 and friends defined

The header provides _MIPS_SIM_ABI32 and friends. Glibc indirectly includes
the header through sys/syscall.h or unistd.h, but let's explicitly include
the header where we use _MIPS_SIM_ABI32 and friends.

src/include/override/sys/generate-syscall.py

@@ -44,6 +44,10 @@ HEADER = '''\
 
 #include_next <sys/syscall.h>
 
+#ifdef ARCH_MIPS
+#include <asm/sgidefs.h>
+#endif
+
 #include <assert.h>
 '''
 

src/include/override/sys/syscall.h

@@ -8,6 +8,10 @@
 
 #include_next <sys/syscall.h>
 
+#ifdef ARCH_MIPS
+#include <asm/sgidefs.h>
+#endif
+
 #include <assert.h>
 
 /* Note: if this code looks strange, this is because it is derived from the same