Firefox 8.0.1 compilation error

hi, I had already compiled Firefox 19.0.2 without any error. But with the same development environment, Firefox 8.0.1 is throwing the following error during compilation, /usr/bin/ld: cannot find -lpthread collect2: ld returned 1 exit status make[7]: *** [dump_syms] Error 1 make[7]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release/obj-linux-firefox-Final/toolkit/crashreporter/google-breakpad/src/tools/linux/dump_syms' make[6]: *** [libs] Error 2 make[6]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release/obj-linux-firefox-Final/toolkit/crashreporter' make[5]: *** [crashreporter_libs] Error 2 make[5]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release/obj-linux-firefox-Final/toolkit' make[4]: *** [libs_tier_platform] Error 2 make[4]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release/obj-linux-firefox-Final' make[3]: *** [tier_platform] Error 2 make[3]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release/obj-linux-firefox-Final' make[2]: *** [default] Error 2 make[2]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release/obj-linux-firefox-Final' make[1]: *** [realbuild] Error 2 make[1]: Leaving directory `/root/Desktop/Firefox_Source/Firefox8.0.1/Source/mozilla-release' make: *** [build] Error 2 Please help me to solve this error...