add math.h to boolean_problem.cc
add math.h to boolean_problem.cc

WendellDuncan/or-tools,ThatRfernand/or-tools,ThatRfernand/or-tools,legrosbuffle/or-tools,WendellDuncan/or-tools,or-tools/or-tools,or-tools/or-tools,ThatRfernand/or-tools,WendellDuncan/or-tools,legrosbuffle/or-tools,google/or-tools,legrosbuffle/or-tools,ThatRfernand/or-tools,or-tools/or-tools,google/or-tools,google/or-tools,or-tools/or-tools,or-tools/or-tools,WendellDuncan/or-tools,legrosbuffle/or-tools,legrosbuffle/or-tools,WendellDuncan/or-tools,google/or-tools,google/or-tools,or-tools/or-tools,google/or-tools,ThatRfernand/or-tools,WendellDuncan/or-tools