Use a constructor function instead of one called _init.

This allows us to compile without -nostdlib, which is causing a lot of
issues.

Reviewed-By: hjk

src/plugins/debugger/ptracepreload.c

@@ -6,7 +6,9 @@
 #include <sys/prctl.h>
 #include <sys/types.h>
 
-int _init(void)
+int ptracepreload_init(void) __attribute__((constructor,visibility("hidden")));
+
+int ptracepreload_init(void)
 {
     prctl(0x59616d61, getppid(), 0, 0, 0);
     puts("eeks\n");

src/plugins/debugger/ptracepreload.pro

@@ -7,8 +7,6 @@ CONFIG += shared
 CONFIG -= qt
 DESTDIR = $$IDE_LIBRARY_PATH
 
-QMAKE_LFLAGS -= -Wl,--as-needed
-QMAKE_LFLAGS *= -nostdlib
 LIBS += -ldl -lc
 
 SOURCES = ptracepreload.c