building in IOS via cmake is 10x slower than qmake 

i don't know why but in cmake there are thousands of not found error when building like below 

warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/ETenms-B5-V_0.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_ETenms_B5_V_0
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/HKscs-B5-H_5.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_HKscs_B5_H_5
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/HKscs-B5-V_5.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_HKscs_B5_V_5
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/UniCNS-UCS2-H_3.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_UniCNS_UCS2_H_3
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/UniCNS-UCS2-V_3.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_UniCNS_UCS2_V_3
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/UniCNS-UTF16-H_0.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_UniCNS_UTF16_H_0
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/cmaps_cns1.o unable to open object file: No such file or directory
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_CNS1_cmaps_size
warning: (x86_64)  could not find object file symbol for symbol _kFXCMAP_CNS1_cmaps
warning: (x86_64) /Users/qt/work/qt/qtwebengine/build/target/src/pdf/Debug/x86_64/obj/third_party/pdfium/core/fpdfapi/cmaps/cmaps/Adobe-GB1-UCS2_5.o unable to open object file: No such file or directory

in Qmake it doesn't happend , it compiles in seconds , but in cmake it tooks me 5-10 minutes to finish the compilation .