fix(install): restore musl support

LaszloGombos · johannbg · commit ce55a85ed5d9 · 2022-03-01T22:25:53.000Z
__GLIBC_PREREQ is only defined in glibc.
diff --git a/src/install/util.c b/src/install/util.c
@@ -24,17 +24,15 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/types.h>
+#include <sys/syscall.h>
 
 #include "util.h"
 
-#if __GLIBC_PREREQ(2, 30) == 0
-#include <sys/syscall.h>
 #ifndef SYS_gettid
 #error "SYS_gettid unavailable on this system"
 #endif
 
 #define gettid()    ((pid_t) syscall(SYS_gettid))
-#endif /*__GLIBC_PREREQ */
 
 size_t page_size(void)
 {
