have_library: checking for main() in -lpthread... -------------------- yes

"gcc -o conftest -I/home/piousbox/.rbenv/versions/2.3.1/include/ruby-2.3.0/x86_64-linux -I/home/piousbox/.rbenv/versions/2.3.1/include/ruby-2.3.0/ruby/backward -I/home/piousbox/.rbenv/versions/2.3.1/include/ruby-2.3.0 -I. -I/home/piousbox/.rbenv/versions/2.3.1/include     -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wno-packed-bitfield-compat conftest.c  -L. -L/home/piousbox/.rbenv/versions/2.3.1/lib -Wl,-R/home/piousbox/.rbenv/versions/2.3.1/lib -L. -L/home/piousbox/.rbenv/versions/2.3.1/lib  -fstack-protector -rdynamic -Wl,-export-dynamic     -Wl,-R/home/piousbox/.rbenv/versions/2.3.1/lib -L/home/piousbox/.rbenv/versions/2.3.1/lib -lruby-static  -lpthread -lgmp -ldl -lcrypt -lm   -lc"
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: int main(int argc, char **argv)
4: {
5:   return 0;
6: }
/* end */

"gcc -o conftest -I/home/piousbox/.rbenv/versions/2.3.1/include/ruby-2.3.0/x86_64-linux -I/home/piousbox/.rbenv/versions/2.3.1/include/ruby-2.3.0/ruby/backward -I/home/piousbox/.rbenv/versions/2.3.1/include/ruby-2.3.0 -I. -I/home/piousbox/.rbenv/versions/2.3.1/include     -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wno-packed-bitfield-compat conftest.c  -L. -L/home/piousbox/.rbenv/versions/2.3.1/lib -Wl,-R/home/piousbox/.rbenv/versions/2.3.1/lib -L. -L/home/piousbox/.rbenv/versions/2.3.1/lib  -fstack-protector -rdynamic -Wl,-export-dynamic     -Wl,-R/home/piousbox/.rbenv/versions/2.3.1/lib -L/home/piousbox/.rbenv/versions/2.3.1/lib -lruby-static -lpthread  -lpthread -lgmp -ldl -lcrypt -lm   -lc"
checked program was:
/* begin */
 1: #include "ruby.h"
 2: 
 3: /*top*/
 4: extern int t(void);
 5: int main(int argc, char **argv)
 6: {
 7:   if (argc > 1000000) {
 8:     printf("%p", &t);
 9:   }
10: 
11:   return 0;
12: }
13: int t(void) { void ((*volatile p)()); p = (void ((*)()))main; return !p; }
/* end */

--------------------