Add -lpthread to the r_core pkgconfig ##build

Author: radare

pkgcfg/r_core.pc.acr

@@ -7,6 +7,6 @@ Name: r_core
 Description: radare foundation libraries
 Version: @VERSION@
 Requires: r_config r_cons r_io r_util r_flag r_asm r_debug r_bin r_lang r_io r_anal r_bp r_egg r_reg r_search r_syscall r_socket r_fs r_magic r_crypto r_arch r_esil
-Libs: -L${libdir} -lr_core -lm @SSL_LDFLAGS@ @CAPSTONE_LDFLAGS@
-Libs.private: -L${libdir} ${libdir}/libr.a
+Libs: -L${libdir} -lr_core -lm @SSL_LDFLAGS@ @CAPSTONE_LDFLAGS@ -lpthread
+Libs.private: -L${libdir} ${libdir}/libr.a -lpthread
 Cflags: -I${includedir}/libr @SSL_CFLAGS@ @CAPSTONE_CFLAGS@